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<a href="checkpt__timer_8hpp.html">Go to the documentation of this file.</a><div class="fragment"><div class="line"><a id="l00001" name="l00001"></a><span class="lineno">    1</span><span class="comment">/* Flow</span></div>
<div class="line"><a id="l00002" name="l00002"></a><span class="lineno">    2</span><span class="comment"> * Copyright 2023 Akamai Technologies, Inc.</span></div>
<div class="line"><a id="l00003" name="l00003"></a><span class="lineno">    3</span><span class="comment"> *</span></div>
<div class="line"><a id="l00004" name="l00004"></a><span class="lineno">    4</span><span class="comment"> * Licensed under the Apache License, Version 2.0 (the</span></div>
<div class="line"><a id="l00005" name="l00005"></a><span class="lineno">    5</span><span class="comment"> * &quot;License&quot;); you may not use this file except in</span></div>
<div class="line"><a id="l00006" name="l00006"></a><span class="lineno">    6</span><span class="comment"> * compliance with the License.  You may obtain a copy</span></div>
<div class="line"><a id="l00007" name="l00007"></a><span class="lineno">    7</span><span class="comment"> * of the License at</span></div>
<div class="line"><a id="l00008" name="l00008"></a><span class="lineno">    8</span><span class="comment"> *</span></div>
<div class="line"><a id="l00009" name="l00009"></a><span class="lineno">    9</span><span class="comment"> *   https://www.apache.org/licenses/LICENSE-2.0</span></div>
<div class="line"><a id="l00010" name="l00010"></a><span class="lineno">   10</span><span class="comment"> *</span></div>
<div class="line"><a id="l00011" name="l00011"></a><span class="lineno">   11</span><span class="comment"> * Unless required by applicable law or agreed to in</span></div>
<div class="line"><a id="l00012" name="l00012"></a><span class="lineno">   12</span><span class="comment"> * writing, software distributed under the License is</span></div>
<div class="line"><a id="l00013" name="l00013"></a><span class="lineno">   13</span><span class="comment"> * distributed on an &quot;AS IS&quot; BASIS, WITHOUT WARRANTIES OR</span></div>
<div class="line"><a id="l00014" name="l00014"></a><span class="lineno">   14</span><span class="comment"> * CONDITIONS OF ANY KIND, either express or implied.</span></div>
<div class="line"><a id="l00015" name="l00015"></a><span class="lineno">   15</span><span class="comment"> * See the License for the specific language governing</span></div>
<div class="line"><a id="l00016" name="l00016"></a><span class="lineno">   16</span><span class="comment"> * permissions and limitations under the License. */</span></div>
<div class="line"><a id="l00017" name="l00017"></a><span class="lineno">   17</span><span class="comment"></span> </div>
<div class="line"><a id="l00018" name="l00018"></a><span class="lineno">   18</span><span class="comment">/// @file</span></div>
<div class="line"><a id="l00019" name="l00019"></a><span class="lineno">   19</span><span class="comment"></span><span class="preprocessor">#pragma once</span></div>
<div class="line"><a id="l00020" name="l00020"></a><span class="lineno">   20</span> </div>
<div class="line"><a id="l00021" name="l00021"></a><span class="lineno">   21</span><span class="preprocessor">#include &quot;<a class="code" href="perf__fwd_8hpp.html">flow/perf/perf_fwd.hpp</a>&quot;</span></div>
<div class="line"><a id="l00022" name="l00022"></a><span class="lineno">   22</span><span class="preprocessor">#include &quot;<a class="code" href="clock__type__fwd_8hpp.html">flow/perf/clock_type_fwd.hpp</a>&quot;</span></div>
<div class="line"><a id="l00023" name="l00023"></a><span class="lineno">   23</span><span class="preprocessor">#include &quot;<a class="code" href="log_8hpp.html">flow/log/log.hpp</a>&quot;</span></div>
<div class="line"><a id="l00024" name="l00024"></a><span class="lineno">   24</span><span class="preprocessor">#include &lt;boost/chrono/process_cpu_clocks.hpp&gt;</span></div>
<div class="line"><a id="l00025" name="l00025"></a><span class="lineno">   25</span><span class="preprocessor">#include &lt;string&gt;</span></div>
<div class="line"><a id="l00026" name="l00026"></a><span class="lineno">   26</span><span class="preprocessor">#include &lt;vector&gt;</span></div>
<div class="line"><a id="l00027" name="l00027"></a><span class="lineno">   27</span> </div>
<div class="line"><a id="l00028" name="l00028"></a><span class="lineno">   28</span><span class="keyword">namespace </span><a class="code hl_namespace" href="namespaceflow_1_1perf.html">flow::perf</a></div>
<div class="line"><a id="l00029" name="l00029"></a><span class="lineno">   29</span>{</div>
<div class="line"><a id="l00030" name="l00030"></a><span class="lineno">   30</span><span class="comment"></span> </div>
<div class="line"><a id="l00031" name="l00031"></a><span class="lineno">   31</span><span class="comment">/**</span></div>
<div class="line"><a id="l00032" name="l00032"></a><span class="lineno">   32</span><span class="comment"> * The central class in the `perf` Flow module, this efficiently times the user&#39;s operation, with a specified subset</span></div>
<div class="line"><a id="l00033" name="l00033"></a><span class="lineno">   33</span><span class="comment"> * of timing methods; and with the optional ability to time intermediate *checkpoints* within the overall operation.</span></div>
<div class="line"><a id="l00034" name="l00034"></a><span class="lineno">   34</span><span class="comment"> *</span></div>
<div class="line"><a id="l00035" name="l00035"></a><span class="lineno">   35</span><span class="comment"> * ### How to use ###</span></div>
<div class="line"><a id="l00036" name="l00036"></a><span class="lineno">   36</span><span class="comment"> * To use this: Construct a Checkpointing_timer; perform the operation in question; then access results via accessors;</span></div>
<div class="line"><a id="l00037" name="l00037"></a><span class="lineno">   37</span><span class="comment"> * including in particular the string/stream output operation that lays out results in human-friendly fashion.</span></div>
<div class="line"><a id="l00038" name="l00038"></a><span class="lineno">   38</span><span class="comment"> * Optionally, call checkpoint() to mark down intermediate timing results, so that the operation can be broken down</span></div>
<div class="line"><a id="l00039" name="l00039"></a><span class="lineno">   39</span><span class="comment"> * into its component parts (the string/stream output will include these).  This is optional, except that at least</span></div>
<div class="line"><a id="l00040" name="l00040"></a><span class="lineno">   40</span><span class="comment"> * 1 checkpoint is required: the last checkpoint represents the end of the measured operation.</span></div>
<div class="line"><a id="l00041" name="l00041"></a><span class="lineno">   41</span><span class="comment"> *</span></div>
<div class="line"><a id="l00042" name="l00042"></a><span class="lineno">   42</span><span class="comment"> * The actual measurements are performed by sampling a time stamp from *each* of N clocks, where N &lt;= M, and M is the</span></div>
<div class="line"><a id="l00043" name="l00043"></a><span class="lineno">   43</span><span class="comment"> * number of values in perf::Clock_type `enum`.  The N clocks are specified at construction by user; thus can measure</span></div>
<div class="line"><a id="l00044" name="l00044"></a><span class="lineno">   44</span><span class="comment"> * just 1, in particular, as is often desired.  This is a critical and potentially subtle decision; see doc headers</span></div>
<div class="line"><a id="l00045" name="l00045"></a><span class="lineno">   45</span><span class="comment"> * of each perf::Clock_type member for tips.</span></div>
<div class="line"><a id="l00046" name="l00046"></a><span class="lineno">   46</span><span class="comment"> *</span></div>
<div class="line"><a id="l00047" name="l00047"></a><span class="lineno">   47</span><span class="comment"> * ### Performance ###</span></div>
<div class="line"><a id="l00048" name="l00048"></a><span class="lineno">   48</span><span class="comment"> * This is a performance-measuring facility, and the performance of a performance-measuring-thing is quite important,</span></div>
<div class="line"><a id="l00049" name="l00049"></a><span class="lineno">   49</span><span class="comment"> * especially since some of the things being timed can be very quick (single-digit microseconds potentially).</span></div>
<div class="line"><a id="l00050" name="l00050"></a><span class="lineno">   50</span><span class="comment"> *</span></div>
<div class="line"><a id="l00051" name="l00051"></a><span class="lineno">   51</span><span class="comment"> * Extreme care has been taken to keep the computational fat of all the book-keeping in the class very low</span></div>
<div class="line"><a id="l00052" name="l00052"></a><span class="lineno">   52</span><span class="comment"> * (and empirical testing shows this was successful).  In the cases where user cooperation is necessary to avoid undoing</span></div>
<div class="line"><a id="l00053" name="l00053"></a><span class="lineno">   53</span><span class="comment"> * this, the doc headers point it out.  Please read docs carefully to avoid timing-technique traps that might lead to</span></div>
<div class="line"><a id="l00054" name="l00054"></a><span class="lineno">   54</span><span class="comment"> * wrong conclusions and frustration.</span></div>
<div class="line"><a id="l00055" name="l00055"></a><span class="lineno">   55</span><span class="comment"> *</span></div>
<div class="line"><a id="l00056" name="l00056"></a><span class="lineno">   56</span><span class="comment"> * ### Thread safety ###</span></div>
<div class="line"><a id="l00057" name="l00057"></a><span class="lineno">   57</span><span class="comment"> * Checkpointing_timer itself is not thread-safe for non-`const` access to an object while any other access occurs</span></div>
<div class="line"><a id="l00058" name="l00058"></a><span class="lineno">   58</span><span class="comment"> * concurrently.  (Internally, there is no locking.)  However, the nature of how one uses a timer object is that</span></div>
<div class="line"><a id="l00059" name="l00059"></a><span class="lineno">   59</span><span class="comment"> * one does stuff to be measured, checkpoint(), more stuff, checkpoint(), ..., final checkpoint().  In other words,</span></div>
<div class="line"><a id="l00060" name="l00060"></a><span class="lineno">   60</span><span class="comment"> * by its very nature, it expects only sequential non-`const` calls while measuring times -- so thread safety</span></div>
<div class="line"><a id="l00061" name="l00061"></a><span class="lineno">   61</span><span class="comment"> * should not come up.  (However, thread safety enters the picture with Checkpointing_timer::Aggregator; see below.)</span></div>
<div class="line"><a id="l00062" name="l00062"></a><span class="lineno">   62</span><span class="comment"> *</span></div>
<div class="line"><a id="l00063" name="l00063"></a><span class="lineno">   63</span><span class="comment"> * Aggregation</span></div>
<div class="line"><a id="l00064" name="l00064"></a><span class="lineno">   64</span><span class="comment"> * -----------</span></div>
<div class="line"><a id="l00065" name="l00065"></a><span class="lineno">   65</span><span class="comment"> * `Duration` result *aggregation* is the common-sense idea that to accurately measure the typical length of operation X</span></div>
<div class="line"><a id="l00066" name="l00066"></a><span class="lineno">   66</span><span class="comment"> * is to repeat X many times (N times) and then view a sum-over-N-samples and/or mean-over-N-samples and/or</span></div>
<div class="line"><a id="l00067" name="l00067"></a><span class="lineno">   67</span><span class="comment"> * mean-over-N-samples-scaled-times-M, where M is usually some convenience constant like 1,000,000.  There are</span></div>
<div class="line"><a id="l00068" name="l00068"></a><span class="lineno">   68</span><span class="comment"> * two patterns we provide/suggest to accomplish aggregation.</span></div>
<div class="line"><a id="l00069" name="l00069"></a><span class="lineno">   69</span><span class="comment"> *</span></div>
<div class="line"><a id="l00070" name="l00070"></a><span class="lineno">   70</span><span class="comment"> * ### Lowest-overhead aggregation approach: Single Checkpointing_timer ###</span></div>
<div class="line"><a id="l00071" name="l00071"></a><span class="lineno">   71</span><span class="comment"> * Suppose you have operation X and are *not* interested in subdividing it into checkpoints; you only care about the</span></div>
<div class="line"><a id="l00072" name="l00072"></a><span class="lineno">   72</span><span class="comment"> * total duration(s) (according to which `Clock_type`s interest you).  Then the following technique leads to the</span></div>
<div class="line"><a id="l00073" name="l00073"></a><span class="lineno">   73</span><span class="comment"> * lowest possible overhead:</span></div>
<div class="line"><a id="l00074" name="l00074"></a><span class="lineno">   74</span><span class="comment"> *</span></div>
<div class="line"><a id="l00075" name="l00075"></a><span class="lineno">   75</span><span class="comment"> *   ~~~</span></div>
<div class="line"><a id="l00076" name="l00076"></a><span class="lineno">   76</span><span class="comment"> *   flow::perf::Checkpointing_timer sum_timer(logger, &quot;op name&quot;, which_clocks, 1); // 1 checkpoint only.</span></div>
<div class="line"><a id="l00077" name="l00077"></a><span class="lineno">   77</span><span class="comment"> *   const unsigned int n_samples = 1000000;</span></div>
<div class="line"><a id="l00078" name="l00078"></a><span class="lineno">   78</span><span class="comment"> *   for (unsigned int sample_idx = 0; sample_idx != n_samples; ++sample_idx)</span></div>
<div class="line"><a id="l00079" name="l00079"></a><span class="lineno">   79</span><span class="comment"> *   {</span></div>
<div class="line"><a id="l00080" name="l00080"></a><span class="lineno">   80</span><span class="comment"> *     // ...Operation X being measured goes here.</span></div>
<div class="line"><a id="l00081" name="l00081"></a><span class="lineno">   81</span><span class="comment"> *   }</span></div>
<div class="line"><a id="l00082" name="l00082"></a><span class="lineno">   82</span><span class="comment"> *   sum_timer.checkpoint(&quot;total&quot;); // Mark down the total time taken.</span></div>
<div class="line"><a id="l00083" name="l00083"></a><span class="lineno">   83</span><span class="comment"> *   // Log the total duration(s), one per clock type!</span></div>
<div class="line"><a id="l00084" name="l00084"></a><span class="lineno">   84</span><span class="comment"> *   flow::perf::Checkpointing_timer::Aggregator::log_aggregated_result_in_timer(sum_timer, n_samples, false);</span></div>
<div class="line"><a id="l00085" name="l00085"></a><span class="lineno">   85</span><span class="comment"> *   // And/or: Log mean duration(s), times N_SAMPLES_SCALE_CONVENIENCE, one per clock type!</span></div>
<div class="line"><a id="l00086" name="l00086"></a><span class="lineno">   86</span><span class="comment"> *   {</span></div>
<div class="line"><a id="l00087" name="l00087"></a><span class="lineno">   87</span><span class="comment"> *     // Just make a copy of the raw sum, then scale it x N_SAMPLES_SCALE_CONVENIENCE / n_samples.</span></div>
<div class="line"><a id="l00088" name="l00088"></a><span class="lineno">   88</span><span class="comment"> *     auto mean_scaled_timer(sum_timer);</span></div>
<div class="line"><a id="l00089" name="l00089"></a><span class="lineno">   89</span><span class="comment"> *     mean_scaled_timer.scale(N_SAMPLES_SCALE_CONVENIENCE, n_samples);</span></div>
<div class="line"><a id="l00090" name="l00090"></a><span class="lineno">   90</span><span class="comment"> *     flow::perf::Checkpointing_timer::Aggregator::log_aggregated_result_in_timer(mean_scaled_timer, n_samples,</span></div>
<div class="line"><a id="l00091" name="l00091"></a><span class="lineno">   91</span><span class="comment"> *                                                                                 true, N_SAMPLES_SCALE_CONVENIENCE);</span></div>
<div class="line"><a id="l00092" name="l00092"></a><span class="lineno">   92</span><span class="comment"> *   }</span></div>
<div class="line"><a id="l00093" name="l00093"></a><span class="lineno">   93</span><span class="comment"> *   ~~~</span></div>
<div class="line"><a id="l00094" name="l00094"></a><span class="lineno">   94</span><span class="comment"> *</span></div>
<div class="line"><a id="l00095" name="l00095"></a><span class="lineno">   95</span><span class="comment"> * This involves minimal overhead, as no timing calls occur at all until X is repeated a million times.</span></div>
<div class="line"><a id="l00096" name="l00096"></a><span class="lineno">   96</span><span class="comment"> *</span></div>
<div class="line"><a id="l00097" name="l00097"></a><span class="lineno">   97</span><span class="comment"> * ### Cross-product aggregation approach: Multiple `Checkpointing_timer`s + Checkpointing_timer::Aggregator ###</span></div>
<div class="line"><a id="l00098" name="l00098"></a><span class="lineno">   98</span><span class="comment"> * If, by contrast, you want to divide X into checkpoints and see (say) how long checkpoint 3 takes on average</span></div>
<div class="line"><a id="l00099" name="l00099"></a><span class="lineno">   99</span><span class="comment"> * (as well as the total as above), then use the dedicated Checkpointing_timer::Aggregator class for that purpose.</span></div>
<div class="line"><a id="l00100" name="l00100"></a><span class="lineno">  100</span><span class="comment"> * This approach also allows one to do stuff (possibly unrelated stuff) between the many repetitions of operation X.</span></div>
<div class="line"><a id="l00101" name="l00101"></a><span class="lineno">  101</span><span class="comment"> * Only X itself will be timed.</span></div>
<div class="line"><a id="l00102" name="l00102"></a><span class="lineno">  102</span><span class="comment"> *</span></div>
<div class="line"><a id="l00103" name="l00103"></a><span class="lineno">  103</span><span class="comment"> * To use `Aggregator`, construct one; then simply create a Checkpointing_timer for each repetition of X and time it</span></div>
<div class="line"><a id="l00104" name="l00104"></a><span class="lineno">  104</span><span class="comment"> * as normal.  Before or after each repetition, register it inside the agg using Aggregator::aggregate() which takes</span></div>
<div class="line"><a id="l00105" name="l00105"></a><span class="lineno">  105</span><span class="comment"> * a pointer to Checkpointing_timer.  The only requirement is that the number and respective names of the checkpoints</span></div>
<div class="line"><a id="l00106" name="l00106"></a><span class="lineno">  106</span><span class="comment"> * in each Checkpointing_timer are the same for all of them.</span></div>
<div class="line"><a id="l00107" name="l00107"></a><span class="lineno">  107</span><span class="comment"> *</span></div>
<div class="line"><a id="l00108" name="l00108"></a><span class="lineno">  108</span><span class="comment"> * Once enough samples (`n_samples` in earlier example) have been thus collected, Aggregator::log_aggregated_results()</span></div>
<div class="line"><a id="l00109" name="l00109"></a><span class="lineno">  109</span><span class="comment"> * will log every potential form (sum, mean, scaled-mean), not just for the total operation X but also</span></div>
<div class="line"><a id="l00110" name="l00110"></a><span class="lineno">  110</span><span class="comment"> * each checkpoint().  For example, if X consists of steps X1, X2, X3, then one would see the mean duration of X1,</span></div>
<div class="line"><a id="l00111" name="l00111"></a><span class="lineno">  111</span><span class="comment"> * X2, and X3 individually and their means would add up to the mean for all of X.</span></div>
<div class="line"><a id="l00112" name="l00112"></a><span class="lineno">  112</span><span class="comment"> *</span></div>
<div class="line"><a id="l00113" name="l00113"></a><span class="lineno">  113</span><span class="comment"> * This is quite powerful; and while the overhead of creating individual Checkpointing_timer objects, say, *might*</span></div>
<div class="line"><a id="l00114" name="l00114"></a><span class="lineno">  114</span><span class="comment"> * affect the overall performance of the algorithm involving X, it shouldn&#39;t have any direct effect on the values</span></div>
<div class="line"><a id="l00115" name="l00115"></a><span class="lineno">  115</span><span class="comment"> * actually being measured, since only each X invocation itself is measured; stuff in-between (slow or not) isn&#39;t.</span></div>
<div class="line"><a id="l00116" name="l00116"></a><span class="lineno">  116</span><span class="comment"> * However:</span></div>
<div class="line"><a id="l00117" name="l00117"></a><span class="lineno">  117</span><span class="comment"> *   - Checkpointing_timer::Aggregator::aggregate() isn&#39;t thread-safe for concurrent access (so if that&#39;s relevant,</span></div>
<div class="line"><a id="l00118" name="l00118"></a><span class="lineno">  118</span><span class="comment"> *     you&#39;ll need a mutex lock around the call).</span></div>
<div class="line"><a id="l00119" name="l00119"></a><span class="lineno">  119</span><span class="comment"> *   - Always ensure you understand the structure of your measurement plan as it relates to concurrency.</span></div>
<div class="line"><a id="l00120" name="l00120"></a><span class="lineno">  120</span><span class="comment"> *     For example, it&#39;s meaningless to measure processor-time cost of X being done repeatedly, if various incarnations</span></div>
<div class="line"><a id="l00121" name="l00121"></a><span class="lineno">  121</span><span class="comment"> *     of X might be performed partially concurrently (say, if X = handling 1 HTTP request in a multi-threaded server</span></div>
<div class="line"><a id="l00122" name="l00122"></a><span class="lineno">  122</span><span class="comment"> *     under load).  In that case processor-times will overlap and produce essentially meaningless (at the very least</span></div>
<div class="line"><a id="l00123" name="l00123"></a><span class="lineno">  123</span><span class="comment"> *     misleading) results.  On the other hand, real-time measurements (Clock_type::S_REAL_HI_RES) make plenty of sense</span></div>
<div class="line"><a id="l00124" name="l00124"></a><span class="lineno">  124</span><span class="comment"> *     in that situation and would indeed reliably measure latency.  Thread-time measurements</span></div>
<div class="line"><a id="l00125" name="l00125"></a><span class="lineno">  125</span><span class="comment"> *     (Clock_type::S_CPU_THREAD_TOTAL_HI_RES) can also make sense.  Just saying: do not assume all clock types</span></div>
<div class="line"><a id="l00126" name="l00126"></a><span class="lineno">  126</span><span class="comment"> *     make sense in the face of concurrent operations; plan mindfully.</span></div>
<div class="line"><a id="l00127" name="l00127"></a><span class="lineno">  127</span><span class="comment"> *</span></div>
<div class="line"><a id="l00128" name="l00128"></a><span class="lineno">  128</span><span class="comment"> * @see Checkpointing_timer::Aggregator.</span></div>
<div class="line"><a id="l00129" name="l00129"></a><span class="lineno">  129</span><span class="comment"> *</span></div>
<div class="line"><a id="l00130" name="l00130"></a><span class="lineno">  130</span><span class="comment"> * @internal</span></div>
<div class="line"><a id="l00131" name="l00131"></a><span class="lineno">  131</span><span class="comment"> *</span></div>
<div class="line"><a id="l00132" name="l00132"></a><span class="lineno">  132</span><span class="comment"> * Implementation/design notes</span></div>
<div class="line"><a id="l00133" name="l00133"></a><span class="lineno">  133</span><span class="comment"> * ---------------------------</span></div>
<div class="line"><a id="l00134" name="l00134"></a><span class="lineno">  134</span><span class="comment"> * On the one hand we wanted to be able to measure multiple clock types; and since at least some of them are</span></div>
<div class="line"><a id="l00135" name="l00135"></a><span class="lineno">  135</span><span class="comment"> * mutually complementary (Clock_type::S_CPU_USER_LO_RES and Clock_type::S_CPU_SYS_LO_RES happen to measure the</span></div>
<div class="line"><a id="l00136" name="l00136"></a><span class="lineno">  136</span><span class="comment"> * user + kernel components of overall processor-time) they need to be sampled simultaneously.  On the other hand</span></div>
<div class="line"><a id="l00137" name="l00137"></a><span class="lineno">  137</span><span class="comment"> * we know clock sampling itself can take non-trivial time; so it must be possible to specify the clocks of interest.</span></div>
<div class="line"><a id="l00138" name="l00138"></a><span class="lineno">  138</span><span class="comment"> *</span></div>
<div class="line"><a id="l00139" name="l00139"></a><span class="lineno">  139</span><span class="comment"> * Also, we wanted to be able to programmatically and/or via logs provide convenient human access to the results,</span></div>
<div class="line"><a id="l00140" name="l00140"></a><span class="lineno">  140</span><span class="comment"> * including optional ability to time the various parts of a multi-step operation and then see which part took how</span></div>
<div class="line"><a id="l00141" name="l00141"></a><span class="lineno">  141</span><span class="comment"> * long; a/k/a checkpoints.</span></div>
<div class="line"><a id="l00142" name="l00142"></a><span class="lineno">  142</span><span class="comment"> *</span></div>
<div class="line"><a id="l00143" name="l00143"></a><span class="lineno">  143</span><span class="comment"> * On the other hand it all needs to be maximally fast, adding very low overhead to the operation being measured.</span></div>
<div class="line"><a id="l00144" name="l00144"></a><span class="lineno">  144</span><span class="comment"> * The way I thought of this was considering the absolute bare minimum of measuring durations: one simply samples the</span></div>
<div class="line"><a id="l00145" name="l00145"></a><span class="lineno">  145</span><span class="comment"> * clock and records it somehow very fast (stack variable perhaps); then at the end one can take time point differences</span></div>
<div class="line"><a id="l00146" name="l00146"></a><span class="lineno">  146</span><span class="comment"> * and log some durations.  This is the minimum; so every computational addition to that must be considered for impact.</span></div>
<div class="line"><a id="l00147" name="l00147"></a><span class="lineno">  147</span><span class="comment"> * In the end, it was successful; as measured by actually raw-timing the timing facilities.  How is this accomplished?</span></div>
<div class="line"><a id="l00148" name="l00148"></a><span class="lineno">  148</span><span class="comment"> *</span></div>
<div class="line"><a id="l00149" name="l00149"></a><span class="lineno">  149</span><span class="comment"> *   - The core operation is checkpoint(), when a final or intermediate time point is sampled; so that&#39;s the thing</span></div>
<div class="line"><a id="l00150" name="l00150"></a><span class="lineno">  150</span><span class="comment"> *     that must be fast.</span></div>
<div class="line"><a id="l00151" name="l00151"></a><span class="lineno">  151</span><span class="comment"> *   - Each sample is recorded in a Duration_set which is a *statically* sized array of N `Duration` values;</span></div>
<div class="line"><a id="l00152" name="l00152"></a><span class="lineno">  152</span><span class="comment"> *     and each Duration (chrono.duration) is a simple nanosecond (or whatever is the unit of flow::Fine_clock, but</span></div>
<div class="line"><a id="l00153" name="l00153"></a><span class="lineno">  153</span><span class="comment"> *     let&#39;s say nanoseconds) count; N is the # of clocks available.</span></div>
<div class="line"><a id="l00154" name="l00154"></a><span class="lineno">  154</span><span class="comment"> *   - The samples are recorded in a simple `vector&lt;&gt;`, so basically it is an array of nanosecond (or whatever)</span></div>
<div class="line"><a id="l00155" name="l00155"></a><span class="lineno">  155</span><span class="comment"> *     counts, with no pointer indirection inside each element.</span></div>
<div class="line"><a id="l00156" name="l00156"></a><span class="lineno">  156</span><span class="comment"> *     - Moreover, the `vector&lt;&gt;` is preallocated to be large enough to store the max # of checkpoints.</span></div>
<div class="line"><a id="l00157" name="l00157"></a><span class="lineno">  157</span><span class="comment"> *       The user specifies this maximum at construction, guaranteeing (re-)allocation never occurs while stuff is</span></div>
<div class="line"><a id="l00158" name="l00158"></a><span class="lineno">  158</span><span class="comment"> *       being timed.  In other words checkpoint() -- when it gets down to the low level of what is actually records --</span></div>
<div class="line"><a id="l00159" name="l00159"></a><span class="lineno">  159</span><span class="comment"> *       places the sampled nanosecond count (for each clock) into a preallocated buffer whose address/size doesn&#39;t</span></div>
<div class="line"><a id="l00160" name="l00160"></a><span class="lineno">  160</span><span class="comment"> *       change, at the address that&#39;s simply `i * sizeof(&lt;N nanosecond counts tightly packed&gt;)`, where `i` is the</span></div>
<div class="line"><a id="l00161" name="l00161"></a><span class="lineno">  161</span><span class="comment"> *       count of checkpoints already recorded.</span></div>
<div class="line"><a id="l00162" name="l00162"></a><span class="lineno">  162</span><span class="comment"> *   - In a nod to the goal of making things human-readable, we add one more thing into the data structures explained</span></div>
<div class="line"><a id="l00163" name="l00163"></a><span class="lineno">  163</span><span class="comment"> *     so far.  Each checkpoint (of which there is at least 1, the final one indicating total elapsed time) therefore</span></div>
<div class="line"><a id="l00164" name="l00164"></a><span class="lineno">  164</span><span class="comment"> *     has a string name supplied by user in checkpoint() call.  Hence instead of storing the `Duration_set`s</span></div>
<div class="line"><a id="l00165" name="l00165"></a><span class="lineno">  165</span><span class="comment"> *     directly in the array, instead a Checkpoint `struct` wraps the Duration_set and name; but this doesn&#39;t add any</span></div>
<div class="line"><a id="l00166" name="l00166"></a><span class="lineno">  166</span><span class="comment"> *     per-sample pointer indirection, so in term of performance it only increases the above `sizeof()` to (internally)</span></div>
<div class="line"><a id="l00167" name="l00167"></a><span class="lineno">  167</span><span class="comment"> *     also include the `std::string` stuff (probably `char*` pointer and a couple `size_t`s).</span></div>
<div class="line"><a id="l00168" name="l00168"></a><span class="lineno">  168</span><span class="comment"> *     - Using move semantics, the user&#39;s `std::string` is not even copied when it is recorded; only the internal</span></div>
<div class="line"><a id="l00169" name="l00169"></a><span class="lineno">  169</span><span class="comment"> *       `string` buffer pointer and sizes are copied.</span></div>
<div class="line"><a id="l00170" name="l00170"></a><span class="lineno">  170</span><span class="comment"> *     - However, the user must form the `string` in the first place!  This is a potential gotcha albeit only when</span></div>
<div class="line"><a id="l00171" name="l00171"></a><span class="lineno">  171</span><span class="comment"> *       one times very short operations.  I actually performed analysis of the cost of this.  The outcome is as</span></div>
<div class="line"><a id="l00172" name="l00172"></a><span class="lineno">  172</span><span class="comment"> *       follows:</span></div>
<div class="line"><a id="l00173" name="l00173"></a><span class="lineno">  173</span><span class="comment"> *       - A nearly-constant checkpoint name (like this: `T.checkpoint(string(&quot;sample&quot;));`) is essentially free.</span></div>
<div class="line"><a id="l00174" name="l00174"></a><span class="lineno">  174</span><span class="comment"> *       - A dynamically computed checkpoint name, using an improved version of `ostringstream` -</span></div>
<div class="line"><a id="l00175" name="l00175"></a><span class="lineno">  175</span><span class="comment"> *         `T.checkpoint(util::ostream_op_string(&quot;sample&quot;, sample_idx));` - has some cost: ~0.5 microseconds</span></div>
<div class="line"><a id="l00176" name="l00176"></a><span class="lineno">  176</span><span class="comment"> *         per sample (MacBook Pro 2015).  Whether this matters or not depends on the op one is measuring, but</span></div>
<div class="line"><a id="l00177" name="l00177"></a><span class="lineno">  177</span><span class="comment"> *         in my experience it&#39;s significant only for the most subtly-tiny ops.  In any case, the official doc header</span></div>
<div class="line"><a id="l00178" name="l00178"></a><span class="lineno">  178</span><span class="comment"> *         for checkpoint() makes suggestions accordingly.  (Spoiler alert: Ultimately - if necessary - one can always</span></div>
<div class="line"><a id="l00179" name="l00179"></a><span class="lineno">  179</span><span class="comment"> *         use a constant checkpoint name, or construct a dynamic name via ultra-fast C-style `char*` direct-writing.)</span></div>
<div class="line"><a id="l00180" name="l00180"></a><span class="lineno">  180</span><span class="comment"> *</span></div>
<div class="line"><a id="l00181" name="l00181"></a><span class="lineno">  181</span><span class="comment"> * The bottom line is, there&#39;s very low overhead added, as long as the user mindfully provides the max # of checkpoints</span></div>
<div class="line"><a id="l00182" name="l00182"></a><span class="lineno">  182</span><span class="comment"> * at construction; and doesn&#39;t waste time on fancily naming the checkpoints.</span></div>
<div class="line"><a id="l00183" name="l00183"></a><span class="lineno">  183</span><span class="comment"> *</span></div>
<div class="line"><a id="l00184" name="l00184"></a><span class="lineno">  184</span><span class="comment"> * @todo `const std::string&amp;` to `String_view` in all of flow::perf where applicable.  Look into `string&amp;&amp;` also.</span></div>
<div class="line"><a id="l00185" name="l00185"></a><span class="lineno">  185</span><span class="comment"> */</span></div>
<div class="line"><a id="l00186" name="l00186"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html">  186</a></span><span class="keyword">class </span><a class="code hl_class" href="classflow_1_1perf_1_1Checkpointing__timer.html">Checkpointing_timer</a> :</div>
<div class="line"><a id="l00187" name="l00187"></a><span class="lineno">  187</span>  <span class="keyword">public</span> <a class="code hl_class" href="classflow_1_1log_1_1Log__context.html">log::Log_context</a></div>
<div class="line"><a id="l00188" name="l00188"></a><span class="lineno">  188</span>{</div>
<div class="line"><a id="l00189" name="l00189"></a><span class="lineno">  189</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00190" name="l00190"></a><span class="lineno">  190</span> </div>
<div class="line"><a id="l00191" name="l00191"></a><span class="lineno">  191</span>  <span class="comment">// Types.</span></div>
<div class="line"><a id="l00192" name="l00192"></a><span class="lineno">  192</span> </div>
<div class="line"><a id="l00193" name="l00193"></a><span class="lineno">  193</span>  <span class="keyword">class </span><a class="code hl_class" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html">Aggregator</a>; <span class="comment">// Fwd.</span></div>
<div class="line"><a id="l00194" name="l00194"></a><span class="lineno">  194</span><span class="comment"></span> </div>
<div class="line"><a id="l00195" name="l00195"></a><span class="lineno">  195</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00196" name="l00196"></a><span class="lineno">  196</span><span class="comment">   * The entirety of the information recorded with each Checkpointing_timer::checkpoint() call;</span></div>
<div class="line"><a id="l00197" name="l00197"></a><span class="lineno">  197</span><span class="comment">   * it contains the `Duration` values (for each `Clock_type`) with the time elapsed since either</span></div>
<div class="line"><a id="l00198" name="l00198"></a><span class="lineno">  198</span><span class="comment">   * the preceding `T.checkpoint()` or construction.</span></div>
<div class="line"><a id="l00199" name="l00199"></a><span class="lineno">  199</span><span class="comment">   *</span></div>
<div class="line"><a id="l00200" name="l00200"></a><span class="lineno">  200</span><span class="comment">   * User doesn&#39;t usually need to access these, since the string/stream/log facilities of Checkpointing_timer and</span></div>
<div class="line"><a id="l00201" name="l00201"></a><span class="lineno">  201</span><span class="comment">   * Checkpointing_timer::Aggregator would already print out the info; but this provides programmatic access if desired.</span></div>
<div class="line"><a id="l00202" name="l00202"></a><span class="lineno">  202</span><span class="comment">   */</span></div>
<div class="line"><a id="l00203" name="l00203"></a><span class="lineno"><a class="line" href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html">  203</a></span>  <span class="keyword">struct </span><a class="code hl_struct" href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html">Checkpoint</a></div>
<div class="line"><a id="l00204" name="l00204"></a><span class="lineno">  204</span>  {<span class="comment"></span></div>
<div class="line"><a id="l00205" name="l00205"></a><span class="lineno">  205</span><span class="comment">    /// User-supplied name of the checkpoint.</span></div>
<div class="line"><a id="l00206" name="l00206"></a><span class="lineno"><a class="line" href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html#a6c0363e3e1ef330464b87363e4287758">  206</a></span><span class="comment"></span>    <span class="keyword">const</span> std::string <a class="code hl_variable" href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html#a6c0363e3e1ef330464b87363e4287758">m_name</a>;<span class="comment"></span></div>
<div class="line"><a id="l00207" name="l00207"></a><span class="lineno">  207</span><span class="comment">    /**</span></div>
<div class="line"><a id="l00208" name="l00208"></a><span class="lineno">  208</span><span class="comment">     * For the `T.checkpoint()` call that generated `*this`, for each enabled `Clock_type`: Time elapsed since either</span></div>
<div class="line"><a id="l00209" name="l00209"></a><span class="lineno">  209</span><span class="comment">     * the preceding `T.checkpoint()` or (if it&#39;s the first `T.checkpoint()`) since `T` construction.</span></div>
<div class="line"><a id="l00210" name="l00210"></a><span class="lineno">  210</span><span class="comment">     * Zero is recorded for each disabled `Clock_type`.</span></div>
<div class="line"><a id="l00211" name="l00211"></a><span class="lineno">  211</span><span class="comment">     */</span></div>
<div class="line"><a id="l00212" name="l00212"></a><span class="lineno"><a class="line" href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html#aacbec1a1e5600aeac4e7ca876060552f">  212</a></span>    <a class="code hl_struct" href="structflow_1_1perf_1_1Duration__set.html">Duration_set</a> <a class="code hl_variable" href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html#aacbec1a1e5600aeac4e7ca876060552f">m_since_last</a>;</div>
<div class="line"><a id="l00213" name="l00213"></a><span class="lineno">  213</span>  };</div>
<div class="line"><a id="l00214" name="l00214"></a><span class="lineno">  214</span> </div>
<div class="line"><a id="l00215" name="l00215"></a><span class="lineno">  215</span>  <span class="comment">// Constructors/destructor.</span></div>
<div class="line"><a id="l00216" name="l00216"></a><span class="lineno">  216</span><span class="comment"></span> </div>
<div class="line"><a id="l00217" name="l00217"></a><span class="lineno">  217</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00218" name="l00218"></a><span class="lineno">  218</span><span class="comment">   * Constructs a new timer and immediately begins measuring time, in that the next checkpoint() call will record</span></div>
<div class="line"><a id="l00219" name="l00219"></a><span class="lineno">  219</span><span class="comment">   * the time passed since right now.  Please read the following docs to achieve low overhead.</span></div>
<div class="line"><a id="l00220" name="l00220"></a><span class="lineno">  220</span><span class="comment">   *</span></div>
<div class="line"><a id="l00221" name="l00221"></a><span class="lineno">  221</span><span class="comment">   * @param name_moved</span></div>
<div class="line"><a id="l00222" name="l00222"></a><span class="lineno">  222</span><span class="comment">   *        Nickname for the timer, for logging and such.  If you want to preserve your string, pass in a copy:</span></div>
<div class="line"><a id="l00223" name="l00223"></a><span class="lineno">  223</span><span class="comment">   *        `string(your_name_value)`.</span></div>
<div class="line"><a id="l00224" name="l00224"></a><span class="lineno">  224</span><span class="comment">   * @param which_clocks</span></div>
<div class="line"><a id="l00225" name="l00225"></a><span class="lineno">  225</span><span class="comment">   *        The clocks you want sampled in each checkpoint().  Please carefully read the doc headers of all</span></div>
<div class="line"><a id="l00226" name="l00226"></a><span class="lineno">  226</span><span class="comment">   *        perf::Clock_type `enum` members.</span></div>
<div class="line"><a id="l00227" name="l00227"></a><span class="lineno">  227</span><span class="comment">   * @param max_n_checkpoints</span></div>
<div class="line"><a id="l00228" name="l00228"></a><span class="lineno">  228</span><span class="comment">   *        The number of times you shall call checkpoint() shall not exceed this.</span></div>
<div class="line"><a id="l00229" name="l00229"></a><span class="lineno">  229</span><span class="comment">   *        A tight value saves RAM; but more importantly a *correct* upper bound guarantees no internal reallocation</span></div>
<div class="line"><a id="l00230" name="l00230"></a><span class="lineno">  230</span><span class="comment">   *        will occur in checkpoint() which is important for maintaining low overhead.</span></div>
<div class="line"><a id="l00231" name="l00231"></a><span class="lineno">  231</span><span class="comment">   *        `assert()` trips if one breaks this promise.</span></div>
<div class="line"><a id="l00232" name="l00232"></a><span class="lineno">  232</span><span class="comment">   * @param logger_ptr</span></div>
<div class="line"><a id="l00233" name="l00233"></a><span class="lineno">  233</span><span class="comment">   *        Logger to use for subsequently logging.</span></div>
<div class="line"><a id="l00234" name="l00234"></a><span class="lineno">  234</span><span class="comment">   */</span></div>
<div class="line"><a id="l00235" name="l00235"></a><span class="lineno">  235</span>  <span class="keyword">explicit</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#aa9940d8e87883f9985ba18939f833db9">Checkpointing_timer</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr, std::string&amp;&amp; name_moved,</div>
<div class="line"><a id="l00236" name="l00236"></a><span class="lineno">  236</span>                               <a class="code hl_typedef" href="namespaceflow_1_1perf.html#aabd93a8a40158585ed149742d8937601">Clock_types_subset</a> which_clocks, <span class="keywordtype">size_t</span> max_n_checkpoints);</div>
<div class="line"><a id="l00237" name="l00237"></a><span class="lineno">  237</span><span class="comment"></span> </div>
<div class="line"><a id="l00238" name="l00238"></a><span class="lineno">  238</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00239" name="l00239"></a><span class="lineno">  239</span><span class="comment">   * Constructs a timer that is identical to but entirely independent of the source object.</span></div>
<div class="line"><a id="l00240" name="l00240"></a><span class="lineno">  240</span><span class="comment">   * When performed outside of performance-critical sections, this is very useful for data massaging *after*</span></div>
<div class="line"><a id="l00241" name="l00241"></a><span class="lineno">  241</span><span class="comment">   * having completely measured something in a Checkpointing_timer.  E.g., one can create a copy and then</span></div>
<div class="line"><a id="l00242" name="l00242"></a><span class="lineno">  242</span><span class="comment">   * scale() it to obtain a mean, etc.</span></div>
<div class="line"><a id="l00243" name="l00243"></a><span class="lineno">  243</span><span class="comment">   *</span></div>
<div class="line"><a id="l00244" name="l00244"></a><span class="lineno">  244</span><span class="comment">   * @see Checkpointing_timer doc header for discussion of aggregation approaches.</span></div>
<div class="line"><a id="l00245" name="l00245"></a><span class="lineno">  245</span><span class="comment">   *</span></div>
<div class="line"><a id="l00246" name="l00246"></a><span class="lineno">  246</span><span class="comment">   * @param src</span></div>
<div class="line"><a id="l00247" name="l00247"></a><span class="lineno">  247</span><span class="comment">   *        Object to copy.</span></div>
<div class="line"><a id="l00248" name="l00248"></a><span class="lineno">  248</span><span class="comment">   */</span></div>
<div class="line"><a id="l00249" name="l00249"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#a886e2150b2918df43c53d4850205e1c8">  249</a></span>  <span class="keyword">explicit</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a886e2150b2918df43c53d4850205e1c8">Checkpointing_timer</a>(<span class="keyword">const</span> <a class="code hl_class" href="classflow_1_1perf_1_1Checkpointing__timer.html">Checkpointing_timer</a>&amp; src) = <span class="keywordflow">default</span>; <span class="comment">// Yes, do allow EXPLICIT copy construction.</span></div>
<div class="line"><a id="l00250" name="l00250"></a><span class="lineno">  250</span><span class="comment"></span> </div>
<div class="line"><a id="l00251" name="l00251"></a><span class="lineno">  251</span><span class="comment">  /// For now at least there&#39;s no reason for move-construction.</span></div>
<div class="line"><a id="l00252" name="l00252"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#a1d1506c1a9d63fb8f9856a1ce6a2f422">  252</a></span><span class="comment"></span>  <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a1d1506c1a9d63fb8f9856a1ce6a2f422">Checkpointing_timer</a>(<a class="code hl_class" href="classflow_1_1perf_1_1Checkpointing__timer.html">Checkpointing_timer</a>&amp;&amp;) = <span class="keyword">delete</span>;</div>
<div class="line"><a id="l00253" name="l00253"></a><span class="lineno">  253</span> </div>
<div class="line"><a id="l00254" name="l00254"></a><span class="lineno">  254</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00255" name="l00255"></a><span class="lineno">  255</span><span class="comment"></span> </div>
<div class="line"><a id="l00256" name="l00256"></a><span class="lineno">  256</span><span class="comment">  /// Disallow overwriting.  Copy-construction exists for a specific pattern to be possible; no need for this so far.</span></div>
<div class="line"><a id="l00257" name="l00257"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#ac8c6a294890c7b59b79555c8116be552">  257</a></span><span class="comment"></span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#ac8c6a294890c7b59b79555c8116be552">operator=</a>(<span class="keyword">const</span> <a class="code hl_class" href="classflow_1_1perf_1_1Checkpointing__timer.html">Checkpointing_timer</a>&amp;) = <span class="keyword">delete</span>;</div>
<div class="line"><a id="l00258" name="l00258"></a><span class="lineno">  258</span><span class="comment"></span> </div>
<div class="line"><a id="l00259" name="l00259"></a><span class="lineno">  259</span><span class="comment">  /// No copy assignment; no move assignment either.</span></div>
<div class="line"><a id="l00260" name="l00260"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#a4c26ee75e58df6abc3b59083f920897c">  260</a></span><span class="comment"></span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a4c26ee75e58df6abc3b59083f920897c">operator=</a>(<a class="code hl_class" href="classflow_1_1perf_1_1Checkpointing__timer.html">Checkpointing_timer</a>&amp;&amp;) = <span class="keyword">delete</span>;</div>
<div class="line"><a id="l00261" name="l00261"></a><span class="lineno">  261</span><span class="comment"></span> </div>
<div class="line"><a id="l00262" name="l00262"></a><span class="lineno">  262</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00263" name="l00263"></a><span class="lineno">  263</span><span class="comment">   * Returns the bit-set containing only those `Clock_type`s enabled that measure passage of real (wall clock) time.</span></div>
<div class="line"><a id="l00264" name="l00264"></a><span class="lineno">  264</span><span class="comment">   *</span></div>
<div class="line"><a id="l00265" name="l00265"></a><span class="lineno">  265</span><span class="comment">   * ### Rationale ###</span></div>
<div class="line"><a id="l00266" name="l00266"></a><span class="lineno">  266</span><span class="comment">   * One application is when deciding on the constructor `which_clocks` arg (also a `Clock_types_subset`).</span></div>
<div class="line"><a id="l00267" name="l00267"></a><span class="lineno">  267</span><span class="comment">   * If one wants to time some operation in such a way as to make only real-time clocks make sense, and the user is</span></div>
<div class="line"><a id="l00268" name="l00268"></a><span class="lineno">  268</span><span class="comment">   * allowed to control which clock types to sample, then one can do:</span></div>
<div class="line"><a id="l00269" name="l00269"></a><span class="lineno">  269</span><span class="comment">   *</span></div>
<div class="line"><a id="l00270" name="l00270"></a><span class="lineno">  270</span><span class="comment">   *   ~~~</span></div>
<div class="line"><a id="l00271" name="l00271"></a><span class="lineno">  271</span><span class="comment">   *   // They can specify a bitmask the_clock_set_from_config; then we potentially cull that further to exclude all</span></div>
<div class="line"><a id="l00272" name="l00272"></a><span class="lineno">  272</span><span class="comment">   *   // but the real-time clocks, because we feel only those make sense in our timing context.</span></div>
<div class="line"><a id="l00273" name="l00273"></a><span class="lineno">  273</span><span class="comment">   *   const auto which_clocks = Checkpointing_timer::real_clock_types() &amp; the_clock_set_from_config;</span></div>
<div class="line"><a id="l00274" name="l00274"></a><span class="lineno">  274</span><span class="comment">   *   Checkpointing_timer timer(..., which_clocks, ...);</span></div>
<div class="line"><a id="l00275" name="l00275"></a><span class="lineno">  275</span><span class="comment">   *   // The timing has begun....</span></div>
<div class="line"><a id="l00276" name="l00276"></a><span class="lineno">  276</span><span class="comment">   *   ~~~</span></div>
<div class="line"><a id="l00277" name="l00277"></a><span class="lineno">  277</span><span class="comment">   *</span></div>
<div class="line"><a id="l00278" name="l00278"></a><span class="lineno">  278</span><span class="comment">   * @see perf::Clock_type</span></div>
<div class="line"><a id="l00279" name="l00279"></a><span class="lineno">  279</span><span class="comment">   *</span></div>
<div class="line"><a id="l00280" name="l00280"></a><span class="lineno">  280</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00281" name="l00281"></a><span class="lineno">  281</span><span class="comment">   */</span></div>
<div class="line"><a id="l00282" name="l00282"></a><span class="lineno">  282</span>  <span class="keyword">static</span> <a class="code hl_typedef" href="namespaceflow_1_1perf.html#aabd93a8a40158585ed149742d8937601">Clock_types_subset</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a959a0446aa6a0b6db59e9892d8f0a699">real_clock_types</a>();</div>
<div class="line"><a id="l00283" name="l00283"></a><span class="lineno">  283</span><span class="comment"></span> </div>
<div class="line"><a id="l00284" name="l00284"></a><span class="lineno">  284</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00285" name="l00285"></a><span class="lineno">  285</span><span class="comment">   * Returns the bit-set containing only those `Clock_type`s enabled that measure passage of processor time by all</span></div>
<div class="line"><a id="l00286" name="l00286"></a><span class="lineno">  286</span><span class="comment">   * threads of the calling process combined.</span></div>
<div class="line"><a id="l00287" name="l00287"></a><span class="lineno">  287</span><span class="comment">   *</span></div>
<div class="line"><a id="l00288" name="l00288"></a><span class="lineno">  288</span><span class="comment">   * ### Rationale ###</span></div>
<div class="line"><a id="l00289" name="l00289"></a><span class="lineno">  289</span><span class="comment">   * See real_clock_types().</span></div>
<div class="line"><a id="l00290" name="l00290"></a><span class="lineno">  290</span><span class="comment">   *</span></div>
<div class="line"><a id="l00291" name="l00291"></a><span class="lineno">  291</span><span class="comment">   * @see perf::Clock_type</span></div>
<div class="line"><a id="l00292" name="l00292"></a><span class="lineno">  292</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00293" name="l00293"></a><span class="lineno">  293</span><span class="comment">   */</span></div>
<div class="line"><a id="l00294" name="l00294"></a><span class="lineno">  294</span>  <span class="keyword">static</span> <a class="code hl_typedef" href="namespaceflow_1_1perf.html#aabd93a8a40158585ed149742d8937601">Clock_types_subset</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a32ed9864d46708789d7418ab637ff382">process_cpu_clock_types</a>();</div>
<div class="line"><a id="l00295" name="l00295"></a><span class="lineno">  295</span><span class="comment"></span> </div>
<div class="line"><a id="l00296" name="l00296"></a><span class="lineno">  296</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00297" name="l00297"></a><span class="lineno">  297</span><span class="comment">   * Returns the bit-set containing only those `Clock_type`s enabled that measure passage of processor time by the</span></div>
<div class="line"><a id="l00298" name="l00298"></a><span class="lineno">  298</span><span class="comment">   * calling thread.</span></div>
<div class="line"><a id="l00299" name="l00299"></a><span class="lineno">  299</span><span class="comment">   *</span></div>
<div class="line"><a id="l00300" name="l00300"></a><span class="lineno">  300</span><span class="comment">   * ### Rationale ###</span></div>
<div class="line"><a id="l00301" name="l00301"></a><span class="lineno">  301</span><span class="comment">   * See real_clock_types().</span></div>
<div class="line"><a id="l00302" name="l00302"></a><span class="lineno">  302</span><span class="comment">   *</span></div>
<div class="line"><a id="l00303" name="l00303"></a><span class="lineno">  303</span><span class="comment">   * @see perf::Clock_type</span></div>
<div class="line"><a id="l00304" name="l00304"></a><span class="lineno">  304</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00305" name="l00305"></a><span class="lineno">  305</span><span class="comment">   */</span></div>
<div class="line"><a id="l00306" name="l00306"></a><span class="lineno">  306</span>  <span class="keyword">static</span> <a class="code hl_typedef" href="namespaceflow_1_1perf.html#aabd93a8a40158585ed149742d8937601">Clock_types_subset</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#aabebe01d0d5096618a8a7c2cf52320fb">thread_cpu_clock_types</a>(); <span class="comment">// Each clock measures current thread&#39;s CPU cycles.</span></div>
<div class="line"><a id="l00307" name="l00307"></a><span class="lineno">  307</span><span class="comment"></span> </div>
<div class="line"><a id="l00308" name="l00308"></a><span class="lineno">  308</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00309" name="l00309"></a><span class="lineno">  309</span><span class="comment">   * Records a checkpoint, which takes a sample of all enabled `Clock_type`s&#39; clocks and records the corresponding</span></div>
<div class="line"><a id="l00310" name="l00310"></a><span class="lineno">  310</span><span class="comment">   * duration(s) since the last checkpoint() or (if none) since construction.</span></div>
<div class="line"><a id="l00311" name="l00311"></a><span class="lineno">  311</span><span class="comment">   *</span></div>
<div class="line"><a id="l00312" name="l00312"></a><span class="lineno">  312</span><span class="comment">   * In practice, at least one checkpoint() call is required for `*this` to be of any use at all.  The final</span></div>
<div class="line"><a id="l00313" name="l00313"></a><span class="lineno">  313</span><span class="comment">   * checkpoint() call&#39;s sample(s) determine the current value of since_start() which is the duration of the entire</span></div>
<div class="line"><a id="l00314" name="l00314"></a><span class="lineno">  314</span><span class="comment">   * operation, as measured since `*this` construction.  Intermediate calls (ones preceding the final one)</span></div>
<div class="line"><a id="l00315" name="l00315"></a><span class="lineno">  315</span><span class="comment">   * are optional and represent intermediate steps and how long they each took.</span></div>
<div class="line"><a id="l00316" name="l00316"></a><span class="lineno">  316</span><span class="comment">   *</span></div>
<div class="line"><a id="l00317" name="l00317"></a><span class="lineno">  317</span><span class="comment">   * since_start() depends on exactly two things: when `*this` was constructed, and when the last checkpoint() call</span></div>
<div class="line"><a id="l00318" name="l00318"></a><span class="lineno">  318</span><span class="comment">   * (at that time) was made.</span></div>
<div class="line"><a id="l00319" name="l00319"></a><span class="lineno">  319</span><span class="comment">   *</span></div>
<div class="line"><a id="l00320" name="l00320"></a><span class="lineno">  320</span><span class="comment">   * ### Naming vs. performance ###</span></div>
<div class="line"><a id="l00321" name="l00321"></a><span class="lineno">  321</span><span class="comment">   * `name_moved` will be taken via move semantics, meaning no string buffer will be copied, only the pointer(s)</span></div>
<div class="line"><a id="l00322" name="l00322"></a><span class="lineno">  322</span><span class="comment">   * and buffer size scalar(s) inside `std::string`.  This helps performance.  However, to *form* `name_moved`</span></div>
<div class="line"><a id="l00323" name="l00323"></a><span class="lineno">  323</span><span class="comment">   * you will naturally spend some processor cycles which therefore risks slowing down the measured operation and</span></div>
<div class="line"><a id="l00324" name="l00324"></a><span class="lineno">  324</span><span class="comment">   * polluting timing results.  To avoid this, please follow the following suggestions.</span></div>
<div class="line"><a id="l00325" name="l00325"></a><span class="lineno">  325</span><span class="comment">   *</span></div>
<div class="line"><a id="l00326" name="l00326"></a><span class="lineno">  326</span><span class="comment">   *   - Passing a constant string as follows is very cheap: `&quot;some constant&quot;` or `string(&quot;same&quot;)`.</span></div>
<div class="line"><a id="l00327" name="l00327"></a><span class="lineno">  327</span><span class="comment">   *     So if that&#39;s good enough for you, do that.</span></div>
<div class="line"><a id="l00328" name="l00328"></a><span class="lineno">  328</span><span class="comment">   *     - In most STL, due to the `std::string` SSO (optimization which stores a short-enough string directly inside</span></div>
<div class="line"><a id="l00329" name="l00329"></a><span class="lineno">  329</span><span class="comment">   *       the `string` object), if you keep the constant 15 characters or less in length, it&#39;s even cheaper;</span></div>
<div class="line"><a id="l00330" name="l00330"></a><span class="lineno">  330</span><span class="comment">   *       heap is not used as a result.</span></div>
<div class="line"><a id="l00331" name="l00331"></a><span class="lineno">  331</span><span class="comment">   *   - Constructing something via util::ostream_op_string() (and/or util::String_ostream) adds about 500 nanoseconds</span></div>
<div class="line"><a id="l00332" name="l00332"></a><span class="lineno">  332</span><span class="comment">   *     per checkpoint() call (e.g.: `util::ostream_op_string(&quot;some string&quot;, some_int)`) on a 2015 MacBook Pro.</span></div>
<div class="line"><a id="l00333" name="l00333"></a><span class="lineno">  333</span><span class="comment">   *     For many, many timing scenarios such sub-microsecond overheads are no big deal, but watch out if you&#39;re</span></div>
<div class="line"><a id="l00334" name="l00334"></a><span class="lineno">  334</span><span class="comment">   *     measuring something tiny-subtle.</span></div>
<div class="line"><a id="l00335" name="l00335"></a><span class="lineno">  335</span><span class="comment">   *     - If it is a problem, use a constant thing as in previous bullet.  If that isn&#39;t sufficient, you can</span></div>
<div class="line"><a id="l00336" name="l00336"></a><span class="lineno">  336</span><span class="comment">   *       fairly easily use C-style direct-`char*`-writing to do it almost as quickly as that, or at least far closer</span></div>
<div class="line"><a id="l00337" name="l00337"></a><span class="lineno">  337</span><span class="comment">   *       to it than to the (syntactically-pretty but slow-in-*this*-context) stream-based string formation.</span></div>
<div class="line"><a id="l00338" name="l00338"></a><span class="lineno">  338</span><span class="comment">   *</span></div>
<div class="line"><a id="l00339" name="l00339"></a><span class="lineno">  339</span><span class="comment">   * ### Logging ###</span></div>
<div class="line"><a id="l00340" name="l00340"></a><span class="lineno">  340</span><span class="comment">   * It will log a TRACE message.  Hence if TRACE is enabled, timing results might be polluted, as logging can</span></div>
<div class="line"><a id="l00341" name="l00341"></a><span class="lineno">  341</span><span class="comment">   * take non-trivial time.</span></div>
<div class="line"><a id="l00342" name="l00342"></a><span class="lineno">  342</span><span class="comment">   *</span></div>
<div class="line"><a id="l00343" name="l00343"></a><span class="lineno">  343</span><span class="comment">   * @param name_moved</span></div>
<div class="line"><a id="l00344" name="l00344"></a><span class="lineno">  344</span><span class="comment">   *        Nickname for the timer, for logging and such.  If you want to preserve your string, pass in a copy:</span></div>
<div class="line"><a id="l00345" name="l00345"></a><span class="lineno">  345</span><span class="comment">   *        `string(your_name_value)`.  See above regarding perf impact.</span></div>
<div class="line"><a id="l00346" name="l00346"></a><span class="lineno">  346</span><span class="comment">   * @return Reference to immutable new Checkpoint `struct`, as it sits directly inside `*this`.</span></div>
<div class="line"><a id="l00347" name="l00347"></a><span class="lineno">  347</span><span class="comment">   */</span></div>
<div class="line"><a id="l00348" name="l00348"></a><span class="lineno">  348</span>  <span class="keyword">const</span> <a class="code hl_struct" href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html">Checkpoint</a>&amp; <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a9e6078df059d5626ab5774f0a33fbad7">checkpoint</a>(std::string&amp;&amp; name_moved);</div>
<div class="line"><a id="l00349" name="l00349"></a><span class="lineno">  349</span><span class="comment"></span> </div>
<div class="line"><a id="l00350" name="l00350"></a><span class="lineno">  350</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00351" name="l00351"></a><span class="lineno">  351</span><span class="comment">   * Returns the duration(s) (for all enabled `Clock_type`s) between construction and the last checkpoint() call.</span></div>
<div class="line"><a id="l00352" name="l00352"></a><span class="lineno">  352</span><span class="comment">   * Behavior is undefined if checkpoint() has not been called.</span></div>
<div class="line"><a id="l00353" name="l00353"></a><span class="lineno">  353</span><span class="comment">   *</span></div>
<div class="line"><a id="l00354" name="l00354"></a><span class="lineno">  354</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00355" name="l00355"></a><span class="lineno">  355</span><span class="comment">   */</span></div>
<div class="line"><a id="l00356" name="l00356"></a><span class="lineno">  356</span>  <a class="code hl_struct" href="structflow_1_1perf_1_1Duration__set.html">Duration_set</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#afeb1faa0e4962dacf9b6a134191a4933">since_start</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00357" name="l00357"></a><span class="lineno">  357</span><span class="comment"></span> </div>
<div class="line"><a id="l00358" name="l00358"></a><span class="lineno">  358</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00359" name="l00359"></a><span class="lineno">  359</span><span class="comment">   * Returns the checkpoints recorded so far.  This returns a reference and thus avoids a copy.  The reference is</span></div>
<div class="line"><a id="l00360" name="l00360"></a><span class="lineno">  360</span><span class="comment">   * valid until `*this` destroyed.</span></div>
<div class="line"><a id="l00361" name="l00361"></a><span class="lineno">  361</span><span class="comment">   *</span></div>
<div class="line"><a id="l00362" name="l00362"></a><span class="lineno">  362</span><span class="comment">   * @return Checkpoints so far.</span></div>
<div class="line"><a id="l00363" name="l00363"></a><span class="lineno">  363</span><span class="comment">   */</span></div>
<div class="line"><a id="l00364" name="l00364"></a><span class="lineno">  364</span>  <span class="keyword">const</span> std::vector&lt;Checkpoint&gt;&amp; <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a1f03d654924a3724e1f051c119f3767b">checkpoints</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00365" name="l00365"></a><span class="lineno">  365</span><span class="comment"></span> </div>
<div class="line"><a id="l00366" name="l00366"></a><span class="lineno">  366</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00367" name="l00367"></a><span class="lineno">  367</span><span class="comment">   * Called anytime after the last checkpoint(), this modifies the data collected so far to be as if every checkpoint</span></div>
<div class="line"><a id="l00368" name="l00368"></a><span class="lineno">  368</span><span class="comment">   * duration D shortened/lengthened by `mult_scale` and divided by `div_scale`.  For example, if</span></div>
<div class="line"><a id="l00369" name="l00369"></a><span class="lineno">  369</span><span class="comment">   * `float(mult_scale) / float(div_scale) == 0.5`, and 3 checkpoints were recorded as (6s, 4s, 12s)</span></div>
<div class="line"><a id="l00370" name="l00370"></a><span class="lineno">  370</span><span class="comment">   * (`since_start()` = 12s + 4s + 6s = 22s), then after the scale() call the checkpoints will reflect</span></div>
<div class="line"><a id="l00371" name="l00371"></a><span class="lineno">  371</span><span class="comment">   * (3s, 2s, 6s) (`since_start()` == 11s).</span></div>
<div class="line"><a id="l00372" name="l00372"></a><span class="lineno">  372</span><span class="comment">   *</span></div>
<div class="line"><a id="l00373" name="l00373"></a><span class="lineno">  373</span><span class="comment">   * In particular (and the original use case for this -- see doc header), if one recorded operation X repeated</span></div>
<div class="line"><a id="l00374" name="l00374"></a><span class="lineno">  374</span><span class="comment">   * sequentially 100x, with `*this` constructed just before the first iteration and `checkpoint()`ed</span></div>
<div class="line"><a id="l00375" name="l00375"></a><span class="lineno">  375</span><span class="comment">   * just after the 100th, then performing `scale(1, 100)` would effectively result in `*this` representing</span></div>
<div class="line"><a id="l00376" name="l00376"></a><span class="lineno">  376</span><span class="comment">   * the mean duration of a single X iteration.</span></div>
<div class="line"><a id="l00377" name="l00377"></a><span class="lineno">  377</span><span class="comment">   *</span></div>
<div class="line"><a id="l00378" name="l00378"></a><span class="lineno">  378</span><span class="comment">   * Formally, behavior is undefined if one calls checkpoint() after calling scale().  Informally it is likely to</span></div>
<div class="line"><a id="l00379" name="l00379"></a><span class="lineno">  379</span><span class="comment">   * result in nonsensical data for all checkpoints created starting with that one and for since_start().</span></div>
<div class="line"><a id="l00380" name="l00380"></a><span class="lineno">  380</span><span class="comment">   *</span></div>
<div class="line"><a id="l00381" name="l00381"></a><span class="lineno">  381</span><span class="comment">   * @param mult_scale</span></div>
<div class="line"><a id="l00382" name="l00382"></a><span class="lineno">  382</span><span class="comment">   *        The timer data are conceptually multiplied by this, first.</span></div>
<div class="line"><a id="l00383" name="l00383"></a><span class="lineno">  383</span><span class="comment">   * @param div_scale</span></div>
<div class="line"><a id="l00384" name="l00384"></a><span class="lineno">  384</span><span class="comment">   *        The timer data are conceptually divided by this, next.</span></div>
<div class="line"><a id="l00385" name="l00385"></a><span class="lineno">  385</span><span class="comment">   */</span></div>
<div class="line"><a id="l00386" name="l00386"></a><span class="lineno">  386</span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a378be385d0c3dda261c8944551280010">scale</a>(uint64_t mult_scale, uint64_t div_scale);</div>
<div class="line"><a id="l00387" name="l00387"></a><span class="lineno">  387</span><span class="comment"></span> </div>
<div class="line"><a id="l00388" name="l00388"></a><span class="lineno">  388</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00389" name="l00389"></a><span class="lineno">  389</span><span class="comment">   * Sample all currently enabled `Clock_type`s&#39; clocks and return those values, each of which is a time stamp</span></div>
<div class="line"><a id="l00390" name="l00390"></a><span class="lineno">  390</span><span class="comment">   * relative to some Epoch value.  (The Epoch value differs by Clock_type.  Durations can be generated by subtracting</span></div>
<div class="line"><a id="l00391" name="l00391"></a><span class="lineno">  391</span><span class="comment">   * one time point from another which mathematically makes Epoch&#39;s meaning irrelevant.)</span></div>
<div class="line"><a id="l00392" name="l00392"></a><span class="lineno">  392</span><span class="comment">   * The value `Time_pt()` (internally: 0 a/k/a Epoch) is set for the disabled clocks.  In particular checkpoint() will</span></div>
<div class="line"><a id="l00393" name="l00393"></a><span class="lineno">  393</span><span class="comment">   * internally call this.</span></div>
<div class="line"><a id="l00394" name="l00394"></a><span class="lineno">  394</span><span class="comment">   *</span></div>
<div class="line"><a id="l00395" name="l00395"></a><span class="lineno">  395</span><span class="comment">   * ### Rationale ###</span></div>
<div class="line"><a id="l00396" name="l00396"></a><span class="lineno">  396</span><span class="comment">   * It is unusual to use this directly by the user, as absolute time</span></div>
<div class="line"><a id="l00397" name="l00397"></a><span class="lineno">  397</span><span class="comment">   * stamps aren&#39;t useful directly, while since_start(), checkpoints(),</span></div>
<div class="line"><a id="l00398" name="l00398"></a><span class="lineno">  398</span><span class="comment">   * the I/O facilities, etc., provide access to the various computed durations, so one needn&#39;t do the subtracting</span></div>
<div class="line"><a id="l00399" name="l00399"></a><span class="lineno">  399</span><span class="comment">   * manually.  Nevertheless being able to get the raw value is useful for (1) sanity-checking more advanced results;</span></div>
<div class="line"><a id="l00400" name="l00400"></a><span class="lineno">  400</span><span class="comment">   * and (2) to time the timer!  (An example of the latter is when I was comparing the duration of checkpoint()</span></div>
<div class="line"><a id="l00401" name="l00401"></a><span class="lineno">  401</span><span class="comment">   * with a constant `name_moved` vs. a dynamic-stream-created one vs. just getting the time stamp via now() and</span></div>
<div class="line"><a id="l00402" name="l00402"></a><span class="lineno">  402</span><span class="comment">   * not calling checkpoint() at all.)</span></div>
<div class="line"><a id="l00403" name="l00403"></a><span class="lineno">  403</span><span class="comment">   *</span></div>
<div class="line"><a id="l00404" name="l00404"></a><span class="lineno">  404</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00405" name="l00405"></a><span class="lineno">  405</span><span class="comment">   */</span></div>
<div class="line"><a id="l00406" name="l00406"></a><span class="lineno">  406</span>  <a class="code hl_struct" href="structflow_1_1perf_1_1Time__pt__set.html">Time_pt_set</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a3b73f2812c2bf6a27ef2becc13859d73">now</a>() <span class="keyword">const</span>;</div>
<div class="line"><a id="l00407" name="l00407"></a><span class="lineno">  407</span><span class="comment"></span> </div>
<div class="line"><a id="l00408" name="l00408"></a><span class="lineno">  408</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00409" name="l00409"></a><span class="lineno">  409</span><span class="comment">   * Based on the passed in `clock_type` argument, the current time is returned for that one particular clock type.</span></div>
<div class="line"><a id="l00410" name="l00410"></a><span class="lineno">  410</span><span class="comment">   *</span></div>
<div class="line"><a id="l00411" name="l00411"></a><span class="lineno">  411</span><span class="comment">   * @param clock_type</span></div>
<div class="line"><a id="l00412" name="l00412"></a><span class="lineno">  412</span><span class="comment">   *        The type of clock to use.  Please carefully read the doc headers of all</span></div>
<div class="line"><a id="l00413" name="l00413"></a><span class="lineno">  413</span><span class="comment">   *        perf::Clock_type `enum` members.</span></div>
<div class="line"><a id="l00414" name="l00414"></a><span class="lineno">  414</span><span class="comment">   * @return The current time.</span></div>
<div class="line"><a id="l00415" name="l00415"></a><span class="lineno">  415</span><span class="comment">   */</span></div>
<div class="line"><a id="l00416" name="l00416"></a><span class="lineno">  416</span>  <span class="keyword">static</span> <a class="code hl_typedef" href="namespaceflow_1_1perf.html#ace5f154155a7d9d5c112c1a83aa04fb5">Time_pt</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a3b73f2812c2bf6a27ef2becc13859d73">now</a>(<a class="code hl_enumeration" href="namespaceflow_1_1perf.html#ad61fb186191e4bb824d14601d11a2eb0">Clock_type</a> clock_type);</div>
<div class="line"><a id="l00417" name="l00417"></a><span class="lineno">  417</span><span class="comment"></span> </div>
<div class="line"><a id="l00418" name="l00418"></a><span class="lineno">  418</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00419" name="l00419"></a><span class="lineno">  419</span><span class="comment">   * Based on the passed in `which_clocks` argument, the current time is returned for the clock types enabled by it.</span></div>
<div class="line"><a id="l00420" name="l00420"></a><span class="lineno">  420</span><span class="comment">   * Identical to non-`static` now() but `which_clocks` is specified as arg instead of at construction.</span></div>
<div class="line"><a id="l00421" name="l00421"></a><span class="lineno">  421</span><span class="comment">   *</span></div>
<div class="line"><a id="l00422" name="l00422"></a><span class="lineno">  422</span><span class="comment">   * @param which_clocks</span></div>
<div class="line"><a id="l00423" name="l00423"></a><span class="lineno">  423</span><span class="comment">   *        The types of clock to use.  Please carefully read the doc headers of all</span></div>
<div class="line"><a id="l00424" name="l00424"></a><span class="lineno">  424</span><span class="comment">   *        perf::Clock_type `enum` members.</span></div>
<div class="line"><a id="l00425" name="l00425"></a><span class="lineno">  425</span><span class="comment">   * @return The current time or times.</span></div>
<div class="line"><a id="l00426" name="l00426"></a><span class="lineno">  426</span><span class="comment">   */</span></div>
<div class="line"><a id="l00427" name="l00427"></a><span class="lineno">  427</span>  <span class="keyword">static</span> <a class="code hl_struct" href="structflow_1_1perf_1_1Time__pt__set.html">Time_pt_set</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a3b73f2812c2bf6a27ef2becc13859d73">now</a>(<span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow_1_1perf.html#aabd93a8a40158585ed149742d8937601">Clock_types_subset</a>&amp; which_clocks);</div>
<div class="line"><a id="l00428" name="l00428"></a><span class="lineno">  428</span><span class="comment"></span> </div>
<div class="line"><a id="l00429" name="l00429"></a><span class="lineno">  429</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00430" name="l00430"></a><span class="lineno">  430</span><span class="comment">   * Equivalent to `(*os) &lt;&lt; (*this)`.</span></div>
<div class="line"><a id="l00431" name="l00431"></a><span class="lineno">  431</span><span class="comment">   *</span></div>
<div class="line"><a id="l00432" name="l00432"></a><span class="lineno">  432</span><span class="comment">   * @param os</span></div>
<div class="line"><a id="l00433" name="l00433"></a><span class="lineno">  433</span><span class="comment">   *        Pointer to `ostream` to which to write.</span></div>
<div class="line"><a id="l00434" name="l00434"></a><span class="lineno">  434</span><span class="comment">   */</span></div>
<div class="line"><a id="l00435" name="l00435"></a><span class="lineno">  435</span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a07204b9119b94bc10d53a8ba15c44797">output</a>(std::ostream* os) <span class="keyword">const</span>;</div>
<div class="line"><a id="l00436" name="l00436"></a><span class="lineno">  436</span> </div>
<div class="line"><a id="l00437" name="l00437"></a><span class="lineno">  437</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00438" name="l00438"></a><span class="lineno">  438</span><span class="comment"></span> </div>
<div class="line"><a id="l00439" name="l00439"></a><span class="lineno">  439</span><span class="comment">  /// The immutable human-readable name for this timer.  It&#39;s `const` so no need for accessor for now.</span></div>
<div class="line"><a id="l00440" name="l00440"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#a25981d44a91e1315bd92711d6e18a91b">  440</a></span><span class="comment"></span>  <span class="keyword">const</span> std::string <a class="code hl_variable" href="classflow_1_1perf_1_1Checkpointing__timer.html#a25981d44a91e1315bd92711d6e18a91b">m_name</a>;</div>
<div class="line"><a id="l00441" name="l00441"></a><span class="lineno">  441</span> </div>
<div class="line"><a id="l00442" name="l00442"></a><span class="lineno">  442</span><span class="keyword">private</span>:</div>
<div class="line"><a id="l00443" name="l00443"></a><span class="lineno">  443</span>  <span class="comment">// Types.</span></div>
<div class="line"><a id="l00444" name="l00444"></a><span class="lineno">  444</span><span class="comment"></span> </div>
<div class="line"><a id="l00445" name="l00445"></a><span class="lineno">  445</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00446" name="l00446"></a><span class="lineno">  446</span><span class="comment">   * `chrono` clock used, internally, for Clock_type::S_CPU_USER_LO_RES and Clock_type::S_CPU_SYS_LO_RES queries.</span></div>
<div class="line"><a id="l00447" name="l00447"></a><span class="lineno">  447</span><span class="comment">   * It can obtain a measurement of both user and kernel time spent by the process concurrently.</span></div>
<div class="line"><a id="l00448" name="l00448"></a><span class="lineno">  448</span><span class="comment">   * In C++20 this isn&#39;t in std.chrono yet.  Go, boost.chrono!</span></div>
<div class="line"><a id="l00449" name="l00449"></a><span class="lineno">  449</span><span class="comment">   *</span></div>
<div class="line"><a id="l00450" name="l00450"></a><span class="lineno">  450</span><span class="comment">   * @note It returns a &quot;real&quot; time too.  However we use other, better clocks for that.</span></div>
<div class="line"><a id="l00451" name="l00451"></a><span class="lineno">  451</span><span class="comment">   */</span></div>
<div class="line"><a id="l00452" name="l00452"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#ae1983df5bfc263f2d4075e26f95cc544">  452</a></span>  <span class="keyword">using </span><a class="code hl_typedef" href="classflow_1_1perf_1_1Checkpointing__timer.html#ae1983df5bfc263f2d4075e26f95cc544">Cpu_split_clock</a> = boost::chrono::process_cpu_clock;</div>
<div class="line"><a id="l00453" name="l00453"></a><span class="lineno">  453</span><span class="comment"></span> </div>
<div class="line"><a id="l00454" name="l00454"></a><span class="lineno">  454</span><span class="comment">  /// Short-hand for the combo (user/kernel) durations-since-epoch tracked by #Cpu_split_clock.</span></div>
<div class="line"><a id="l00455" name="l00455"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#af14cca9bf47de862b19f04a9348de234">  455</a></span><span class="comment"></span>  <span class="keyword">using </span><a class="code hl_typedef" href="classflow_1_1perf_1_1Checkpointing__timer.html#af14cca9bf47de862b19f04a9348de234">Cpu_split_clock_durs_since_epoch</a> = Cpu_split_clock::times;</div>
<div class="line"><a id="l00456" name="l00456"></a><span class="lineno">  456</span> </div>
<div class="line"><a id="l00457" name="l00457"></a><span class="lineno">  457</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00458" name="l00458"></a><span class="lineno">  458</span><span class="comment"></span> </div>
<div class="line"><a id="l00459" name="l00459"></a><span class="lineno">  459</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00460" name="l00460"></a><span class="lineno">  460</span><span class="comment">   * Returns the current #Cpu_split_clock time, essentially as a combo `struct` containing raw (integer) counts of</span></div>
<div class="line"><a id="l00461" name="l00461"></a><span class="lineno">  461</span><span class="comment">   * user and kernel ticks since that clock&#39;s epoch reference point.</span></div>
<div class="line"><a id="l00462" name="l00462"></a><span class="lineno">  462</span><span class="comment">   *</span></div>
<div class="line"><a id="l00463" name="l00463"></a><span class="lineno">  463</span><span class="comment">   * ### Rationale ###</span></div>
<div class="line"><a id="l00464" name="l00464"></a><span class="lineno">  464</span><span class="comment">   * It&#39;s a helper for performance and accuracy: So we can access the clock only once and be able to able to get the</span></div>
<div class="line"><a id="l00465" name="l00465"></a><span class="lineno">  465</span><span class="comment">   * various values in the result at the same time.  now_cpu_lo_res() can get individual values from the return value</span></div>
<div class="line"><a id="l00466" name="l00466"></a><span class="lineno">  466</span><span class="comment">   * here.</span></div>
<div class="line"><a id="l00467" name="l00467"></a><span class="lineno">  467</span><span class="comment">   *</span></div>
<div class="line"><a id="l00468" name="l00468"></a><span class="lineno">  468</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00469" name="l00469"></a><span class="lineno">  469</span><span class="comment">   */</span></div>
<div class="line"><a id="l00470" name="l00470"></a><span class="lineno">  470</span>  <span class="keyword">static</span> <a class="code hl_typedef" href="classflow_1_1perf_1_1Checkpointing__timer.html#af14cca9bf47de862b19f04a9348de234">Cpu_split_clock_durs_since_epoch</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a7c799f400ceddd5ad5529fa66f026fd0">now_cpu_lo_res_raw</a>();</div>
<div class="line"><a id="l00471" name="l00471"></a><span class="lineno">  471</span><span class="comment"></span> </div>
<div class="line"><a id="l00472" name="l00472"></a><span class="lineno">  472</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00473" name="l00473"></a><span class="lineno">  473</span><span class="comment">   * Returns individual `Time_pt` value returnable by now() various overloads: either the user time or system time</span></div>
<div class="line"><a id="l00474" name="l00474"></a><span class="lineno">  474</span><span class="comment">   * depending on arg.</span></div>
<div class="line"><a id="l00475" name="l00475"></a><span class="lineno">  475</span><span class="comment">   *</span></div>
<div class="line"><a id="l00476" name="l00476"></a><span class="lineno">  476</span><span class="comment">   * @param cpu_combo_now_raw</span></div>
<div class="line"><a id="l00477" name="l00477"></a><span class="lineno">  477</span><span class="comment">   *        Value returned by now_cpu_lo_res_raw() (or equivalent).</span></div>
<div class="line"><a id="l00478" name="l00478"></a><span class="lineno">  478</span><span class="comment">   * @param user_else_sys</span></div>
<div class="line"><a id="l00479" name="l00479"></a><span class="lineno">  479</span><span class="comment">   *        If `true` the user time is returned; else the system time.</span></div>
<div class="line"><a id="l00480" name="l00480"></a><span class="lineno">  480</span><span class="comment">   * @return See above.</span></div>
<div class="line"><a id="l00481" name="l00481"></a><span class="lineno">  481</span><span class="comment">   */</span></div>
<div class="line"><a id="l00482" name="l00482"></a><span class="lineno">  482</span>  <span class="keyword">static</span> <a class="code hl_typedef" href="namespaceflow_1_1perf.html#ace5f154155a7d9d5c112c1a83aa04fb5">Time_pt</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#a82e717d5b1f6df56dc70b26c7da100f3">now_cpu_lo_res</a>(<span class="keyword">const</span> <a class="code hl_typedef" href="classflow_1_1perf_1_1Checkpointing__timer.html#af14cca9bf47de862b19f04a9348de234">Cpu_split_clock_durs_since_epoch</a>&amp; cpu_combo_now_raw, <span class="keywordtype">bool</span> user_else_sys);</div>
<div class="line"><a id="l00483" name="l00483"></a><span class="lineno">  483</span> </div>
<div class="line"><a id="l00484" name="l00484"></a><span class="lineno">  484</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00485" name="l00485"></a><span class="lineno">  485</span><span class="comment"></span> </div>
<div class="line"><a id="l00486" name="l00486"></a><span class="lineno">  486</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00487" name="l00487"></a><span class="lineno">  487</span><span class="comment">   * Aggregator needs access to the Checkpointing_timer innards; generally speaking, stylistically, it is fine.</span></div>
<div class="line"><a id="l00488" name="l00488"></a><span class="lineno">  488</span><span class="comment">   * It is an inner class to reflect that cooperation further.</span></div>
<div class="line"><a id="l00489" name="l00489"></a><span class="lineno">  489</span><span class="comment">   */</span></div>
<div class="line"><a id="l00490" name="l00490"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#af6c863bd15229565be61ed7cb1406b5b">  490</a></span>  <span class="keyword">friend</span> <span class="keyword">class </span><a class="code hl_class" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html">Aggregator</a>;</div>
<div class="line"><a id="l00491" name="l00491"></a><span class="lineno">  491</span><span class="comment"></span> </div>
<div class="line"><a id="l00492" name="l00492"></a><span class="lineno">  492</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00493" name="l00493"></a><span class="lineno">  493</span><span class="comment">   * Internally useful constructor that initializes an ill-formed `*this` without almost no meaningful member values,</span></div>
<div class="line"><a id="l00494" name="l00494"></a><span class="lineno">  494</span><span class="comment">   * specifically useful at least when creating the aggregated Checkpointing_timer from multiple &quot;real&quot; timers,</span></div>
<div class="line"><a id="l00495" name="l00495"></a><span class="lineno">  495</span><span class="comment">   * by Aggregator.  Take care to initialize all fields properly before making</span></div>
<div class="line"><a id="l00496" name="l00496"></a><span class="lineno">  496</span><span class="comment">   * `*this` publicly available.</span></div>
<div class="line"><a id="l00497" name="l00497"></a><span class="lineno">  497</span><span class="comment">   *</span></div>
<div class="line"><a id="l00498" name="l00498"></a><span class="lineno">  498</span><span class="comment">   * @param logger_ptr</span></div>
<div class="line"><a id="l00499" name="l00499"></a><span class="lineno">  499</span><span class="comment">   *        See `public` constructor.</span></div>
<div class="line"><a id="l00500" name="l00500"></a><span class="lineno">  500</span><span class="comment">   * @param name_moved</span></div>
<div class="line"><a id="l00501" name="l00501"></a><span class="lineno">  501</span><span class="comment">   *        See `public` constructor.</span></div>
<div class="line"><a id="l00502" name="l00502"></a><span class="lineno">  502</span><span class="comment">   * @param which_clocks</span></div>
<div class="line"><a id="l00503" name="l00503"></a><span class="lineno">  503</span><span class="comment">   *        See `public` constructor.</span></div>
<div class="line"><a id="l00504" name="l00504"></a><span class="lineno">  504</span><span class="comment">   */</span></div>
<div class="line"><a id="l00505" name="l00505"></a><span class="lineno">  505</span>  <span class="keyword">explicit</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer.html#aa9940d8e87883f9985ba18939f833db9">Checkpointing_timer</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr, std::string&amp;&amp; name_moved, <a class="code hl_typedef" href="namespaceflow_1_1perf.html#aabd93a8a40158585ed149742d8937601">Clock_types_subset</a> which_clocks);</div>
<div class="line"><a id="l00506" name="l00506"></a><span class="lineno">  506</span><span class="comment"></span> </div>
<div class="line"><a id="l00507" name="l00507"></a><span class="lineno">  507</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00508" name="l00508"></a><span class="lineno">  508</span><span class="comment">   * The bit-set indexed by `size_t(Clock_type::...)` wherein that clock will be sampled in now() and checkpoint()</span></div>
<div class="line"><a id="l00509" name="l00509"></a><span class="lineno">  509</span><span class="comment">   * if and only if its bit is set.  All zeroes is allowed and will, accordingly, result in 0 `Duration`s and</span></div>
<div class="line"><a id="l00510" name="l00510"></a><span class="lineno">  510</span><span class="comment">   * `Time_pt`s in all results.  Subtlety: now() doesn&#39;t work properly until this is initialized.</span></div>
<div class="line"><a id="l00511" name="l00511"></a><span class="lineno">  511</span><span class="comment">   */</span></div>
<div class="line"><a id="l00512" name="l00512"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#ac5518c3fdc58f8867ca114186562575b">  512</a></span>  <span class="keyword">const</span> <a class="code hl_typedef" href="namespaceflow_1_1perf.html#aabd93a8a40158585ed149742d8937601">Clock_types_subset</a> <a class="code hl_variable" href="classflow_1_1perf_1_1Checkpointing__timer.html#ac5518c3fdc58f8867ca114186562575b">m_which_clocks</a>;</div>
<div class="line"><a id="l00513" name="l00513"></a><span class="lineno">  513</span><span class="comment"></span> </div>
<div class="line"><a id="l00514" name="l00514"></a><span class="lineno">  514</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00515" name="l00515"></a><span class="lineno">  515</span><span class="comment">   * The value of now() saved in `public` constructor, marking the time point when the timing began.  Doesn&#39;t change</span></div>
<div class="line"><a id="l00516" name="l00516"></a><span class="lineno">  516</span><span class="comment">   * after construction.  since_start() (the total duration(s)) is based on this and #m_start_when.</span></div>
<div class="line"><a id="l00517" name="l00517"></a><span class="lineno">  517</span><span class="comment">   *</span></div>
<div class="line"><a id="l00518" name="l00518"></a><span class="lineno">  518</span><span class="comment">   * Ideally this would be `const` but isn&#39;t for some minor reasons (see `public` constructor).</span></div>
<div class="line"><a id="l00519" name="l00519"></a><span class="lineno">  519</span><span class="comment">   */</span></div>
<div class="line"><a id="l00520" name="l00520"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#ac16b16c3192e287ae3f08be786626f1a">  520</a></span>  <a class="code hl_struct" href="structflow_1_1perf_1_1Time__pt__set.html">Time_pt_set</a> <a class="code hl_variable" href="classflow_1_1perf_1_1Checkpointing__timer.html#ac16b16c3192e287ae3f08be786626f1a">m_start_when</a>;</div>
<div class="line"><a id="l00521" name="l00521"></a><span class="lineno">  521</span><span class="comment"></span> </div>
<div class="line"><a id="l00522" name="l00522"></a><span class="lineno">  522</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00523" name="l00523"></a><span class="lineno">  523</span><span class="comment">   * The value of now() recorded during the last checkpoint() call; or equals #m_start_when if checkpoint() has not</span></div>
<div class="line"><a id="l00524" name="l00524"></a><span class="lineno">  524</span><span class="comment">   * yet been called.  since_start() (the total duration(s)) is based on this and #m_start_when.</span></div>
<div class="line"><a id="l00525" name="l00525"></a><span class="lineno">  525</span><span class="comment">   *</span></div>
<div class="line"><a id="l00526" name="l00526"></a><span class="lineno">  526</span><span class="comment">   * Ideally this would be `const` but had to be left technically mutable due to certain `array&lt;&gt;` initialization</span></div>
<div class="line"><a id="l00527" name="l00527"></a><span class="lineno">  527</span><span class="comment">   * subtleties.</span></div>
<div class="line"><a id="l00528" name="l00528"></a><span class="lineno">  528</span><span class="comment">   */</span></div>
<div class="line"><a id="l00529" name="l00529"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#a66605dd59939ddc69d7f8fde19a5ed7c">  529</a></span>  <a class="code hl_struct" href="structflow_1_1perf_1_1Time__pt__set.html">Time_pt_set</a> <a class="code hl_variable" href="classflow_1_1perf_1_1Checkpointing__timer.html#a66605dd59939ddc69d7f8fde19a5ed7c">m_last_checkpoint_when</a>;</div>
<div class="line"><a id="l00530" name="l00530"></a><span class="lineno">  530</span><span class="comment"></span> </div>
<div class="line"><a id="l00531" name="l00531"></a><span class="lineno">  531</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00532" name="l00532"></a><span class="lineno">  532</span><span class="comment">   * The checkpoints recorded so far, in order, one per checkpoint() call.  To avoid any reallocations, this is</span></div>
<div class="line"><a id="l00533" name="l00533"></a><span class="lineno">  533</span><span class="comment">   * reserved to contain a buffer at least `max_n_checkpoints` (see ctor) elements long.</span></div>
<div class="line"><a id="l00534" name="l00534"></a><span class="lineno">  534</span><span class="comment">   */</span></div>
<div class="line"><a id="l00535" name="l00535"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer.html#a9d064df3b46dd7e629f4d836a9803750">  535</a></span>  std::vector&lt;Checkpoint&gt; <a class="code hl_variable" href="classflow_1_1perf_1_1Checkpointing__timer.html#a9d064df3b46dd7e629f4d836a9803750">m_checkpoints</a>;</div>
<div class="line"><a id="l00536" name="l00536"></a><span class="lineno">  536</span>};</div>
<div class="line"><a id="l00537" name="l00537"></a><span class="lineno">  537</span><span class="comment"></span> </div>
<div class="line"><a id="l00538" name="l00538"></a><span class="lineno">  538</span><span class="comment">/**</span></div>
<div class="line"><a id="l00539" name="l00539"></a><span class="lineno">  539</span><span class="comment"> * This companion/inner class of Checkpointing_timer provides aggregation of results from many `Checkpointing_timer`s</span></div>
<div class="line"><a id="l00540" name="l00540"></a><span class="lineno">  540</span><span class="comment"> * each measuring some user operation being repeated many times; particularly when the operation consists of multiple</span></div>
<div class="line"><a id="l00541" name="l00541"></a><span class="lineno">  541</span><span class="comment"> * steps (checkpoints) of interest.</span></div>
<div class="line"><a id="l00542" name="l00542"></a><span class="lineno">  542</span><span class="comment"> *</span></div>
<div class="line"><a id="l00543" name="l00543"></a><span class="lineno">  543</span><span class="comment"> * Please read the aggregation section in Checkpointing_timer doc header before using this.</span></div>
<div class="line"><a id="l00544" name="l00544"></a><span class="lineno">  544</span><span class="comment"> *</span></div>
<div class="line"><a id="l00545" name="l00545"></a><span class="lineno">  545</span><span class="comment"> * One small technical point: To make a Checkpointing_timer X available for `Aggregator::aggregate(X)`, you must</span></div>
<div class="line"><a id="l00546" name="l00546"></a><span class="lineno">  546</span><span class="comment"> * construct it on the heap and provide a Checkpointing_timer_ptr accordingly:</span></div>
<div class="line"><a id="l00547" name="l00547"></a><span class="lineno">  547</span><span class="comment"> *</span></div>
<div class="line"><a id="l00548" name="l00548"></a><span class="lineno">  548</span><span class="comment"> *   ~~~</span></div>
<div class="line"><a id="l00549" name="l00549"></a><span class="lineno">  549</span><span class="comment"> *   Checkpointing_timer_ptr X(new Checkpointing_timer(...));</span></div>
<div class="line"><a id="l00550" name="l00550"></a><span class="lineno">  550</span><span class="comment"> *   ~~~</span></div>
<div class="line"><a id="l00551" name="l00551"></a><span class="lineno">  551</span><span class="comment"> *</span></div>
<div class="line"><a id="l00552" name="l00552"></a><span class="lineno">  552</span><span class="comment"> * ### Thread safety ###</span></div>
<div class="line"><a id="l00553" name="l00553"></a><span class="lineno">  553</span><span class="comment"> * A reiteration of the aforementioned Checkpointing_timer doc header: Non-`const` methods are generally not safe</span></div>
<div class="line"><a id="l00554" name="l00554"></a><span class="lineno">  554</span><span class="comment"> * if called concurrently with any other method on the same Aggregator.  In practice this should only matter for</span></div>
<div class="line"><a id="l00555" name="l00555"></a><span class="lineno">  555</span><span class="comment"> * calling aggregate().  If you are timing things concurrently happening in different threads you may need to add</span></div>
<div class="line"><a id="l00556" name="l00556"></a><span class="lineno">  556</span><span class="comment"> * a mutex lock around aggregate(); and in that case make sure it doesn&#39;t adversely affect your algorithm&#39;s overall</span></div>
<div class="line"><a id="l00557" name="l00557"></a><span class="lineno">  557</span><span class="comment"> * performance (or, if it does, then that is acceptable).</span></div>
<div class="line"><a id="l00558" name="l00558"></a><span class="lineno">  558</span><span class="comment"> */</span></div>
<div class="line"><a id="l00559" name="l00559"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html">  559</a></span><span class="keyword">class </span><a class="code hl_class" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html">Checkpointing_timer::Aggregator</a> :</div>
<div class="line"><a id="l00560" name="l00560"></a><span class="lineno">  560</span>  <span class="keyword">public</span> <a class="code hl_class" href="classflow_1_1log_1_1Log__context.html">flow::log::Log_context</a>,</div>
<div class="line"><a id="l00561" name="l00561"></a><span class="lineno">  561</span>  <span class="keyword">private</span> boost::noncopyable</div>
<div class="line"><a id="l00562" name="l00562"></a><span class="lineno">  562</span>{</div>
<div class="line"><a id="l00563" name="l00563"></a><span class="lineno">  563</span><span class="keyword">public</span>:</div>
<div class="line"><a id="l00564" name="l00564"></a><span class="lineno">  564</span>  <span class="comment">// Constructors/destructor.</span></div>
<div class="line"><a id="l00565" name="l00565"></a><span class="lineno">  565</span><span class="comment"></span> </div>
<div class="line"><a id="l00566" name="l00566"></a><span class="lineno">  566</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00567" name="l00567"></a><span class="lineno">  567</span><span class="comment">   * Constructs a new, empty aggregator.  After this call aggregate() to add source `Checkpointing_timer`s.</span></div>
<div class="line"><a id="l00568" name="l00568"></a><span class="lineno">  568</span><span class="comment">   *</span></div>
<div class="line"><a id="l00569" name="l00569"></a><span class="lineno">  569</span><span class="comment">   * @param name_moved</span></div>
<div class="line"><a id="l00570" name="l00570"></a><span class="lineno">  570</span><span class="comment">   *        Nickname for the agg, for logging and such.</span></div>
<div class="line"><a id="l00571" name="l00571"></a><span class="lineno">  571</span><span class="comment">   * @param max_n_samples</span></div>
<div class="line"><a id="l00572" name="l00572"></a><span class="lineno">  572</span><span class="comment">   *        The number of times you shall call aggregate() shall not exceed this.</span></div>
<div class="line"><a id="l00573" name="l00573"></a><span class="lineno">  573</span><span class="comment">   *        See similar (in spirit) `max_n_checkpoints` in Checkpointing_timer constructor.</span></div>
<div class="line"><a id="l00574" name="l00574"></a><span class="lineno">  574</span><span class="comment">   * @param logger_ptr</span></div>
<div class="line"><a id="l00575" name="l00575"></a><span class="lineno">  575</span><span class="comment">   *        Logger to use for subsequently logging.</span></div>
<div class="line"><a id="l00576" name="l00576"></a><span class="lineno">  576</span><span class="comment">   */</span></div>
<div class="line"><a id="l00577" name="l00577"></a><span class="lineno">  577</span>  <span class="keyword">explicit</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#adbe0250e405ae2be4b434f5e2cb76f7a">Aggregator</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr, std::string&amp;&amp; name_moved, <span class="keywordtype">size_t</span> max_n_samples);</div>
<div class="line"><a id="l00578" name="l00578"></a><span class="lineno">  578</span> </div>
<div class="line"><a id="l00579" name="l00579"></a><span class="lineno">  579</span>  <span class="comment">// Methods.</span></div>
<div class="line"><a id="l00580" name="l00580"></a><span class="lineno">  580</span><span class="comment"></span> </div>
<div class="line"><a id="l00581" name="l00581"></a><span class="lineno">  581</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00582" name="l00582"></a><span class="lineno">  582</span><span class="comment">   * Register given Checkpointing_timer for aggregated results.  The best time to call this is immediately after</span></div>
<div class="line"><a id="l00583" name="l00583"></a><span class="lineno">  583</span><span class="comment">   * the last `timer_ptr-&gt;checkpoint()` call, as that way the call itself won&#39;t be included in the timer&#39;s duration(s).</span></div>
<div class="line"><a id="l00584" name="l00584"></a><span class="lineno">  584</span><span class="comment">   *</span></div>
<div class="line"><a id="l00585" name="l00585"></a><span class="lineno">  585</span><span class="comment">   * The second best time to call it is immediately after `*timer_ptr` is constructed; the call is quite cheap, so</span></div>
<div class="line"><a id="l00586" name="l00586"></a><span class="lineno">  586</span><span class="comment">   * it really shouldn&#39;t affect results much.  The third best time is somewhere between those 2 points in time; in that</span></div>
<div class="line"><a id="l00587" name="l00587"></a><span class="lineno">  587</span><span class="comment">   * case its (quite small, probably negligible) time cost will be charged to whatever checkpoint was &quot;running&quot; at the</span></div>
<div class="line"><a id="l00588" name="l00588"></a><span class="lineno">  588</span><span class="comment">   * time.</span></div>
<div class="line"><a id="l00589" name="l00589"></a><span class="lineno">  589</span><span class="comment">   *</span></div>
<div class="line"><a id="l00590" name="l00590"></a><span class="lineno">  590</span><span class="comment">   * ### Requirements on aggregated timers ###</span></div>
<div class="line"><a id="l00591" name="l00591"></a><span class="lineno">  591</span><span class="comment">   * In and of itself `*timer_ptr` can be any Checkpointing_timer with at least one checkpoint() call done.</span></div>
<div class="line"><a id="l00592" name="l00592"></a><span class="lineno">  592</span><span class="comment">   * In addition, behavior is undefined in log_aggregated_results() and create_aggregated_result() unless all of the</span></div>
<div class="line"><a id="l00593" name="l00593"></a><span class="lineno">  593</span><span class="comment">   * following hold about all `aggregate()`d timers at the time of those calls.</span></div>
<div class="line"><a id="l00594" name="l00594"></a><span class="lineno">  594</span><span class="comment">   *   - Their `which_clocks` values (as passed to Checkpointing_timer constructor) are all equal.</span></div>
<div class="line"><a id="l00595" name="l00595"></a><span class="lineno">  595</span><span class="comment">   *   - They each have the same number of checkpoints.</span></div>
<div class="line"><a id="l00596" name="l00596"></a><span class="lineno">  596</span><span class="comment">   *   - For each `i`: Their `i`-th Checkpointing_timer::Checkpoint::m_name values are all mutually equal.</span></div>
<div class="line"><a id="l00597" name="l00597"></a><span class="lineno">  597</span><span class="comment">   *</span></div>
<div class="line"><a id="l00598" name="l00598"></a><span class="lineno">  598</span><span class="comment">   * Since aggregation collates the many measurements of the same multi-step operation, these should all be common</span></div>
<div class="line"><a id="l00599" name="l00599"></a><span class="lineno">  599</span><span class="comment">   * sense; if one doesn&#39;t hold for you, there is some kind of very basic problem.</span></div>
<div class="line"><a id="l00600" name="l00600"></a><span class="lineno">  600</span><span class="comment">   *</span></div>
<div class="line"><a id="l00601" name="l00601"></a><span class="lineno">  601</span><span class="comment">   * ### Thread safety ###</span></div>
<div class="line"><a id="l00602" name="l00602"></a><span class="lineno">  602</span><span class="comment">   * See Aggregator doc header.  A mutex lock around this call may be desirable depending on situation.</span></div>
<div class="line"><a id="l00603" name="l00603"></a><span class="lineno">  603</span><span class="comment">   *</span></div>
<div class="line"><a id="l00604" name="l00604"></a><span class="lineno">  604</span><span class="comment">   * @param timer_ptr</span></div>
<div class="line"><a id="l00605" name="l00605"></a><span class="lineno">  605</span><span class="comment">   *        The timer to register.</span></div>
<div class="line"><a id="l00606" name="l00606"></a><span class="lineno">  606</span><span class="comment">   */</span></div>
<div class="line"><a id="l00607" name="l00607"></a><span class="lineno">  607</span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#a18bdb2f17039bcb82ddd4022a3a8340d">aggregate</a>(<a class="code hl_typedef" href="namespaceflow_1_1perf.html#a09ba385403a0f347f283659a6e9d971b">Checkpointing_timer_ptr</a> timer_ptr);</div>
<div class="line"><a id="l00608" name="l00608"></a><span class="lineno">  608</span><span class="comment"></span> </div>
<div class="line"><a id="l00609" name="l00609"></a><span class="lineno">  609</span><span class="comment">  /// Act as if aggregate() has never been called since construction.</span></div>
<div class="line"><a id="l00610" name="l00610"></a><span class="lineno">  610</span><span class="comment"></span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#aeb9e86afbbf49865c6cce1ae7d2fc7a3">clear</a>();</div>
<div class="line"><a id="l00611" name="l00611"></a><span class="lineno">  611</span><span class="comment"></span> </div>
<div class="line"><a id="l00612" name="l00612"></a><span class="lineno">  612</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00613" name="l00613"></a><span class="lineno">  613</span><span class="comment">   * Called after the final Checkpointing_timer has finished (final `checkpoint()` call) and been `aggregate()`d,</span></div>
<div class="line"><a id="l00614" name="l00614"></a><span class="lineno">  614</span><span class="comment">   * this `INFO`-logs human-friendly readout of the aggregated results so far.  This will include all 3 types of</span></div>
<div class="line"><a id="l00615" name="l00615"></a><span class="lineno">  615</span><span class="comment">   * aggregation: sum; mean; and mean-scaled-by-convenience-constant; or some specified subset thereof.</span></div>
<div class="line"><a id="l00616" name="l00616"></a><span class="lineno">  616</span><span class="comment">   *</span></div>
<div class="line"><a id="l00617" name="l00617"></a><span class="lineno">  617</span><span class="comment">   * ### Performance ###</span></div>
<div class="line"><a id="l00618" name="l00618"></a><span class="lineno">  618</span><span class="comment">   * It is possible to call it between `aggregate()`s, perhaps to output incremental results.  It may be slow and should</span></div>
<div class="line"><a id="l00619" name="l00619"></a><span class="lineno">  619</span><span class="comment">   * not be called within any perf-critical section and definitely not in any measured section.  The most natural</span></div>
<div class="line"><a id="l00620" name="l00620"></a><span class="lineno">  620</span><span class="comment">   * time to call it is after all data collection has finished.</span></div>
<div class="line"><a id="l00621" name="l00621"></a><span class="lineno">  621</span><span class="comment">   *</span></div>
<div class="line"><a id="l00622" name="l00622"></a><span class="lineno">  622</span><span class="comment">   * Tip: you can pass null as the logger to the ctor of each Checkpointing_timer and even the Aggregator</span></div>
<div class="line"><a id="l00623" name="l00623"></a><span class="lineno">  623</span><span class="comment">   * and only use non-null `alternate_logger_ptr_or_null`.  Then the cost of should-log checks will be zero</span></div>
<div class="line"><a id="l00624" name="l00624"></a><span class="lineno">  624</span><span class="comment">   * all over except here (where presumably it does not matter).</span></div>
<div class="line"><a id="l00625" name="l00625"></a><span class="lineno">  625</span><span class="comment">   *</span></div>
<div class="line"><a id="l00626" name="l00626"></a><span class="lineno">  626</span><span class="comment">   * @param alternate_logger_ptr_or_null</span></div>
<div class="line"><a id="l00627" name="l00627"></a><span class="lineno">  627</span><span class="comment">   *        If null, logs are sent to get_logger() as normal; otherwise it is sent to the supplied log::Logger instead.</span></div>
<div class="line"><a id="l00628" name="l00628"></a><span class="lineno">  628</span><span class="comment">   *        Since logging this output is a first-class facility within Checkpointing_timer::Aggregator -- unlike</span></div>
<div class="line"><a id="l00629" name="l00629"></a><span class="lineno">  629</span><span class="comment">   *        vast majority of Flow logging which is a secondary (though important in practice) nicety -- it seemed</span></div>
<div class="line"><a id="l00630" name="l00630"></a><span class="lineno">  630</span><span class="comment">   *        sensible to provide extra control of this particular bit of logging.</span></div>
<div class="line"><a id="l00631" name="l00631"></a><span class="lineno">  631</span><span class="comment">   *        Also note that any (probably TRACE) logging outside of the timer-data output will still go to</span></div>
<div class="line"><a id="l00632" name="l00632"></a><span class="lineno">  632</span><span class="comment">   *        get_logger().</span></div>
<div class="line"><a id="l00633" name="l00633"></a><span class="lineno">  633</span><span class="comment">   * @param show_sum</span></div>
<div class="line"><a id="l00634" name="l00634"></a><span class="lineno">  634</span><span class="comment">   *        Whether to show the SUM aggregated output type.</span></div>
<div class="line"><a id="l00635" name="l00635"></a><span class="lineno">  635</span><span class="comment">   * @param show_mean</span></div>
<div class="line"><a id="l00636" name="l00636"></a><span class="lineno">  636</span><span class="comment">   *        Whether to show the MEAN aggregated output type.</span></div>
<div class="line"><a id="l00637" name="l00637"></a><span class="lineno">  637</span><span class="comment">   * @param mean_scale_or_zero</span></div>
<div class="line"><a id="l00638" name="l00638"></a><span class="lineno">  638</span><span class="comment">   *        If zero do not show SCALED-MEAN aggregated output; otherwise show it, with this value as the</span></div>
<div class="line"><a id="l00639" name="l00639"></a><span class="lineno">  639</span><span class="comment">   *        scale-constant.  (E.g., one could show the average latency per 100,000 requests which might be</span></div>
<div class="line"><a id="l00640" name="l00640"></a><span class="lineno">  640</span><span class="comment">   *        more conveniently large than a per-request mean.)</span></div>
<div class="line"><a id="l00641" name="l00641"></a><span class="lineno">  641</span><span class="comment">   */</span></div>
<div class="line"><a id="l00642" name="l00642"></a><span class="lineno">  642</span>  <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#a29c66da23a48bdb5096bf2f206f5cae4">log_aggregated_results</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* alternate_logger_ptr_or_null,</div>
<div class="line"><a id="l00643" name="l00643"></a><span class="lineno">  643</span>                              <span class="keywordtype">bool</span> show_sum, <span class="keywordtype">bool</span> show_mean, uint64_t mean_scale_or_zero) <span class="keyword">const</span>;</div>
<div class="line"><a id="l00644" name="l00644"></a><span class="lineno">  644</span><span class="comment"></span> </div>
<div class="line"><a id="l00645" name="l00645"></a><span class="lineno">  645</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00646" name="l00646"></a><span class="lineno">  646</span><span class="comment">   * Provides programmatic access to the aggregation result that would be logged by log_aggregated_results() -- in</span></div>
<div class="line"><a id="l00647" name="l00647"></a><span class="lineno">  647</span><span class="comment">   * the form of a returned new Checkpointing_timer that stores those numbers.</span></div>
<div class="line"><a id="l00648" name="l00648"></a><span class="lineno">  648</span><span class="comment">   *</span></div>
<div class="line"><a id="l00649" name="l00649"></a><span class="lineno">  649</span><span class="comment">   * log_aggregated_results() basically calls this once for each type of aggregated data it wants to see.</span></div>
<div class="line"><a id="l00650" name="l00650"></a><span class="lineno">  650</span><span class="comment">   * Accordingly, if you desire programmatic access to type X of aggregated results, call this and specify the</span></div>
<div class="line"><a id="l00651" name="l00651"></a><span class="lineno">  651</span><span class="comment">   * type X of interest, as args.  log_aggregated_results() doc header&#39;s perf notes apply here similarly.</span></div>
<div class="line"><a id="l00652" name="l00652"></a><span class="lineno">  652</span><span class="comment">   *</span></div>
<div class="line"><a id="l00653" name="l00653"></a><span class="lineno">  653</span><span class="comment">   * You can also use `info_log_result` to immediately log the results, as log_aggregated_results() would for that</span></div>
<div class="line"><a id="l00654" name="l00654"></a><span class="lineno">  654</span><span class="comment">   * aggregation type.  Conceivably you could then ignore the return value, depending on your goals.</span></div>
<div class="line"><a id="l00655" name="l00655"></a><span class="lineno">  655</span><span class="comment">   *</span></div>
<div class="line"><a id="l00656" name="l00656"></a><span class="lineno">  656</span><span class="comment">   * @param alternate_logger_ptr_or_null</span></div>
<div class="line"><a id="l00657" name="l00657"></a><span class="lineno">  657</span><span class="comment">   *        Same meaning as for log_aggregated_results().  However here this is only relevant if `info_log_result`;</span></div>
<div class="line"><a id="l00658" name="l00658"></a><span class="lineno">  658</span><span class="comment">   *        otherwise ignored (null is fine).</span></div>
<div class="line"><a id="l00659" name="l00659"></a><span class="lineno">  659</span><span class="comment">   * @param info_log_result</span></div>
<div class="line"><a id="l00660" name="l00660"></a><span class="lineno">  660</span><span class="comment">   *        If and only if `true`, INFO messages are logged with human-readable representation of</span></div>
<div class="line"><a id="l00661" name="l00661"></a><span class="lineno">  661</span><span class="comment">   *        the returned data, similarly to (partial) log_aggregated_results() output.</span></div>
<div class="line"><a id="l00662" name="l00662"></a><span class="lineno">  662</span><span class="comment">   *        Actually it simply calls log_aggregated_result_in_timer() on the returned Checkpointing_timer.</span></div>
<div class="line"><a id="l00663" name="l00663"></a><span class="lineno">  663</span><span class="comment">   * @param mean_scale_or_zero</span></div>
<div class="line"><a id="l00664" name="l00664"></a><span class="lineno">  664</span><span class="comment">   *        If zero then return SUM aggregated output; otherwise MEAN or SCALED-MEAN aggregated output, with this</span></div>
<div class="line"><a id="l00665" name="l00665"></a><span class="lineno">  665</span><span class="comment">   *        value as the scale-constant (the value 1 =&gt; an un-scaled MEAN output).</span></div>
<div class="line"><a id="l00666" name="l00666"></a><span class="lineno">  666</span><span class="comment">   *        (E.g., one could show the average latency per 100,000 requests which might be</span></div>
<div class="line"><a id="l00667" name="l00667"></a><span class="lineno">  667</span><span class="comment">   *        more conveniently large than a per-request mean.)</span></div>
<div class="line"><a id="l00668" name="l00668"></a><span class="lineno">  668</span><span class="comment">   * @return Ref-counted pointer to a new Checkpointing_timer that stores the aggregated results.</span></div>
<div class="line"><a id="l00669" name="l00669"></a><span class="lineno">  669</span><span class="comment">   *         This timer will have the same `which_clocks`, and its `checkpoints()` will have the same length and</span></div>
<div class="line"><a id="l00670" name="l00670"></a><span class="lineno">  670</span><span class="comment">   *         in-order names, as each of the source timers; its name and get_logger() will come from Aggregator `name`</span></div>
<div class="line"><a id="l00671" name="l00671"></a><span class="lineno">  671</span><span class="comment">   *         (ctor arg) and get_logger() respectively.</span></div>
<div class="line"><a id="l00672" name="l00672"></a><span class="lineno">  672</span><span class="comment">   */</span></div>
<div class="line"><a id="l00673" name="l00673"></a><span class="lineno">  673</span>  <a class="code hl_typedef" href="namespaceflow_1_1perf.html#a09ba385403a0f347f283659a6e9d971b">Checkpointing_timer_ptr</a> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#acbacf3b4842b77f542082e7a186f1434">create_aggregated_result</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* alternate_logger_ptr_or_null, <span class="keywordtype">bool</span> info_log_result,</div>
<div class="line"><a id="l00674" name="l00674"></a><span class="lineno">  674</span>                                                   uint64_t mean_scale_or_zero = 1) <span class="keyword">const</span>;</div>
<div class="line"><a id="l00675" name="l00675"></a><span class="lineno">  675</span><span class="comment"></span> </div>
<div class="line"><a id="l00676" name="l00676"></a><span class="lineno">  676</span><span class="comment">  /**</span></div>
<div class="line"><a id="l00677" name="l00677"></a><span class="lineno">  677</span><span class="comment">   * Given an aggregated-result Checkpointing_timer (as if returned by create_aggregated_result()) logs the SUM or MEAN</span></div>
<div class="line"><a id="l00678" name="l00678"></a><span class="lineno">  678</span><span class="comment">   * or SCALED-MEAN stored in it as INFO messages.</span></div>
<div class="line"><a id="l00679" name="l00679"></a><span class="lineno">  679</span><span class="comment">   *</span></div>
<div class="line"><a id="l00680" name="l00680"></a><span class="lineno">  680</span><span class="comment">   * Publicly, it exists for one use case (as of this writing), namely to log a &quot;manually&quot; compiled aggregated-result</span></div>
<div class="line"><a id="l00681" name="l00681"></a><span class="lineno">  681</span><span class="comment">   * Checkpointing_timer.  This *pattern* is explained in the Checkpointing_timer doc header in the aggregation section.</span></div>
<div class="line"><a id="l00682" name="l00682"></a><span class="lineno">  682</span><span class="comment">   *</span></div>
<div class="line"><a id="l00683" name="l00683"></a><span class="lineno">  683</span><span class="comment">   * Naturally, it is also used internally by create_aggregated_result() and log_aggregated_results(), hence why they</span></div>
<div class="line"><a id="l00684" name="l00684"></a><span class="lineno">  684</span><span class="comment">   * all produce similar output.</span></div>
<div class="line"><a id="l00685" name="l00685"></a><span class="lineno">  685</span><span class="comment">   *</span></div>
<div class="line"><a id="l00686" name="l00686"></a><span class="lineno">  686</span><span class="comment">   * @param logger_ptr</span></div>
<div class="line"><a id="l00687" name="l00687"></a><span class="lineno">  687</span><span class="comment">   *        Same meaning as in log_aggregated_results(), except null is not a valid value (behavior is undefined).</span></div>
<div class="line"><a id="l00688" name="l00688"></a><span class="lineno">  688</span><span class="comment">   * @param agg_timer</span></div>
<div class="line"><a id="l00689" name="l00689"></a><span class="lineno">  689</span><span class="comment">   *        Aggregated-result Checkpointing_timer, as if returned by create_aggregated_result().</span></div>
<div class="line"><a id="l00690" name="l00690"></a><span class="lineno">  690</span><span class="comment">   *        Behavior is undefined unless it was, in fact, returned by that method (or is a copy of such);</span></div>
<div class="line"><a id="l00691" name="l00691"></a><span class="lineno">  691</span><span class="comment">   *        or unless it was compiled as described in the aforementioned pattern, documented in Checkpointing_timer</span></div>
<div class="line"><a id="l00692" name="l00692"></a><span class="lineno">  692</span><span class="comment">   *        doc header.</span></div>
<div class="line"><a id="l00693" name="l00693"></a><span class="lineno">  693</span><span class="comment">   * @param n_samples</span></div>
<div class="line"><a id="l00694" name="l00694"></a><span class="lineno">  694</span><span class="comment">   *        For appropriate logging, this must contain the # of samples (repetitions of the measured operation)</span></div>
<div class="line"><a id="l00695" name="l00695"></a><span class="lineno">  695</span><span class="comment">   *        collected to yield `agg_timer`.</span></div>
<div class="line"><a id="l00696" name="l00696"></a><span class="lineno">  696</span><span class="comment">   * @param mean_scale_or_zero</span></div>
<div class="line"><a id="l00697" name="l00697"></a><span class="lineno">  697</span><span class="comment">   *        For appropriate logging, this must contain the type of aggregated numbers that are stored in `agg_timer`.</span></div>
<div class="line"><a id="l00698" name="l00698"></a><span class="lineno">  698</span><span class="comment">   *        See create_aggregated_result().</span></div>
<div class="line"><a id="l00699" name="l00699"></a><span class="lineno">  699</span><span class="comment">   */</span></div>
<div class="line"><a id="l00700" name="l00700"></a><span class="lineno">  700</span>  <span class="keyword">static</span> <span class="keywordtype">void</span> <a class="code hl_function" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#abd543abbfae859ddc111741468f95125">log_aggregated_result_in_timer</a>(<a class="code hl_class" href="classflow_1_1log_1_1Logger.html">log::Logger</a>* logger_ptr,</div>
<div class="line"><a id="l00701" name="l00701"></a><span class="lineno">  701</span>                                             <span class="keyword">const</span> <a class="code hl_class" href="classflow_1_1perf_1_1Checkpointing__timer.html">Checkpointing_timer</a>&amp; agg_timer, <span class="keywordtype">unsigned</span> <span class="keywordtype">int</span> n_samples,</div>
<div class="line"><a id="l00702" name="l00702"></a><span class="lineno">  702</span>                                             uint64_t mean_scale_or_zero = 1);</div>
<div class="line"><a id="l00703" name="l00703"></a><span class="lineno">  703</span> </div>
<div class="line"><a id="l00704" name="l00704"></a><span class="lineno">  704</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00705" name="l00705"></a><span class="lineno">  705</span><span class="comment"></span> </div>
<div class="line"><a id="l00706" name="l00706"></a><span class="lineno">  706</span><span class="comment">  /// The immutable human-readable name for this timer.  It&#39;s `const` so no need for accessor for now.</span></div>
<div class="line"><a id="l00707" name="l00707"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#a6ea09e3aa22c8e4ba234f465bdc0e0fd">  707</a></span><span class="comment"></span>  <span class="keyword">const</span> std::string <a class="code hl_variable" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#a6ea09e3aa22c8e4ba234f465bdc0e0fd">m_name</a>;</div>
<div class="line"><a id="l00708" name="l00708"></a><span class="lineno">  708</span> </div>
<div class="line"><a id="l00709" name="l00709"></a><span class="lineno">  709</span><span class="keyword">private</span>:</div>
<div class="line"><a id="l00710" name="l00710"></a><span class="lineno">  710</span>  <span class="comment">// Data.</span></div>
<div class="line"><a id="l00711" name="l00711"></a><span class="lineno">  711</span><span class="comment"></span> </div>
<div class="line"><a id="l00712" name="l00712"></a><span class="lineno">  712</span><span class="comment">  /// The ref-counted pointers to source timers passed to aggregate() in that order.</span></div>
<div class="line"><a id="l00713" name="l00713"></a><span class="lineno"><a class="line" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#af1c4f46ce680b979e98a3e255c88d063">  713</a></span><span class="comment"></span>  std::vector&lt;Checkpointing_timer_ptr&gt; <a class="code hl_variable" href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#af1c4f46ce680b979e98a3e255c88d063">m_timers</a>;</div>
<div class="line"><a id="l00714" name="l00714"></a><span class="lineno">  714</span>}; <span class="comment">// class Checkpointing_timer::Aggregator</span></div>
<div class="line"><a id="l00715" name="l00715"></a><span class="lineno">  715</span> </div>
<div class="line"><a id="l00716" name="l00716"></a><span class="lineno">  716</span><span class="comment">// Free functions: in *_fwd.hpp.</span></div>
<div class="line"><a id="l00717" name="l00717"></a><span class="lineno">  717</span> </div>
<div class="line"><a id="l00718" name="l00718"></a><span class="lineno">  718</span><span class="comment">// However the following refer to inner class and hence must be declared here and not _fwd.hpp.</span></div>
<div class="line"><a id="l00719" name="l00719"></a><span class="lineno">  719</span><span class="comment"></span> </div>
<div class="line"><a id="l00720" name="l00720"></a><span class="lineno">  720</span><span class="comment">/**</span></div>
<div class="line"><a id="l00721" name="l00721"></a><span class="lineno">  721</span><span class="comment"> * Prints string representation of the given `Checkpoint` to the given `ostream`.  See</span></div>
<div class="line"><a id="l00722" name="l00722"></a><span class="lineno">  722</span><span class="comment"> * Checkpointing_timer::checkpoint() and Checkpointing_timer::checkpoints().</span></div>
<div class="line"><a id="l00723" name="l00723"></a><span class="lineno">  723</span><span class="comment"> *</span></div>
<div class="line"><a id="l00724" name="l00724"></a><span class="lineno">  724</span><span class="comment"> * @relatesalso Checkpointing_timer::Checkpoint</span></div>
<div class="line"><a id="l00725" name="l00725"></a><span class="lineno">  725</span><span class="comment"> *</span></div>
<div class="line"><a id="l00726" name="l00726"></a><span class="lineno">  726</span><span class="comment"> * @param os</span></div>
<div class="line"><a id="l00727" name="l00727"></a><span class="lineno">  727</span><span class="comment"> *        Stream to which to write.</span></div>
<div class="line"><a id="l00728" name="l00728"></a><span class="lineno">  728</span><span class="comment"> * @param checkpoint</span></div>
<div class="line"><a id="l00729" name="l00729"></a><span class="lineno">  729</span><span class="comment"> *        Object to serialize.</span></div>
<div class="line"><a id="l00730" name="l00730"></a><span class="lineno">  730</span><span class="comment"> * @return `os`.</span></div>
<div class="line"><a id="l00731" name="l00731"></a><span class="lineno">  731</span><span class="comment"> */</span></div>
<div class="line"><a id="l00732" name="l00732"></a><span class="lineno">  732</span>std::ostream&amp; <a class="code hl_function" href="namespaceflow_1_1perf.html#a5bb3a068357516df714c4266ec5c3df4">operator&lt;&lt;</a>(std::ostream&amp; os, <span class="keyword">const</span> <a class="code hl_struct" href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html">Checkpointing_timer::Checkpoint</a>&amp; checkpoint);</div>
<div class="line"><a id="l00733" name="l00733"></a><span class="lineno">  733</span> </div>
<div class="line"><a id="l00734" name="l00734"></a><span class="lineno">  734</span>} <span class="comment">// namespace flow::perf</span></div>
<div class="ttc" id="aclassflow_1_1log_1_1Log__context_html"><div class="ttname"><a href="classflow_1_1log_1_1Log__context.html">flow::log::Log_context</a></div><div class="ttdoc">Convenience class that simply stores a Logger and/or Component passed into a constructor; and returns...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01609">log.hpp:1610</a></div></div>
<div class="ttc" id="aclassflow_1_1log_1_1Logger_html"><div class="ttname"><a href="classflow_1_1log_1_1Logger.html">flow::log::Logger</a></div><div class="ttdoc">Interface that the user should implement, passing the implementing Logger into logging classes (Flow'...</div><div class="ttdef"><b>Definition:</b> <a href="log_8hpp_source.html#l01280">log.hpp:1284</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator_html"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html">flow::perf::Checkpointing_timer::Aggregator</a></div><div class="ttdoc">This companion/inner class of Checkpointing_timer provides aggregation of results from many Checkpoin...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00559">checkpt_timer.hpp:562</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator_html_a18bdb2f17039bcb82ddd4022a3a8340d"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#a18bdb2f17039bcb82ddd4022a3a8340d">flow::perf::Checkpointing_timer::Aggregator::aggregate</a></div><div class="ttdeci">void aggregate(Checkpointing_timer_ptr timer_ptr)</div><div class="ttdoc">Register given Checkpointing_timer for aggregated results.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00357">checkpt_timer.cpp:357</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator_html_a29c66da23a48bdb5096bf2f206f5cae4"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#a29c66da23a48bdb5096bf2f206f5cae4">flow::perf::Checkpointing_timer::Aggregator::log_aggregated_results</a></div><div class="ttdeci">void log_aggregated_results(log::Logger *alternate_logger_ptr_or_null, bool show_sum, bool show_mean, uint64_t mean_scale_or_zero) const</div><div class="ttdoc">Called after the final Checkpointing_timer has finished (final checkpoint() call) and been aggregate(...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00506">checkpt_timer.cpp:506</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator_html_a6ea09e3aa22c8e4ba234f465bdc0e0fd"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#a6ea09e3aa22c8e4ba234f465bdc0e0fd">flow::perf::Checkpointing_timer::Aggregator::m_name</a></div><div class="ttdeci">const std::string m_name</div><div class="ttdoc">The immutable human-readable name for this timer. It's const so no need for accessor for now.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00707">checkpt_timer.hpp:707</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator_html_abd543abbfae859ddc111741468f95125"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#abd543abbfae859ddc111741468f95125">flow::perf::Checkpointing_timer::Aggregator::log_aggregated_result_in_timer</a></div><div class="ttdeci">static void log_aggregated_result_in_timer(log::Logger *logger_ptr, const Checkpointing_timer &amp;agg_timer, unsigned int n_samples, uint64_t mean_scale_or_zero=1)</div><div class="ttdoc">Given an aggregated-result Checkpointing_timer (as if returned by create_aggregated_result()) logs th...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00470">checkpt_timer.cpp:471</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator_html_acbacf3b4842b77f542082e7a186f1434"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#acbacf3b4842b77f542082e7a186f1434">flow::perf::Checkpointing_timer::Aggregator::create_aggregated_result</a></div><div class="ttdeci">Checkpointing_timer_ptr create_aggregated_result(log::Logger *alternate_logger_ptr_or_null, bool info_log_result, uint64_t mean_scale_or_zero=1) const</div><div class="ttdoc">Provides programmatic access to the aggregation result that would be logged by log_aggregated_results...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00371">checkpt_timer.cpp:372</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator_html_adbe0250e405ae2be4b434f5e2cb76f7a"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#adbe0250e405ae2be4b434f5e2cb76f7a">flow::perf::Checkpointing_timer::Aggregator::Aggregator</a></div><div class="ttdeci">Aggregator(log::Logger *logger_ptr, std::string &amp;&amp;name_moved, size_t max_n_samples)</div><div class="ttdoc">Constructs a new, empty aggregator.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00348">checkpt_timer.cpp:348</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator_html_aeb9e86afbbf49865c6cce1ae7d2fc7a3"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#aeb9e86afbbf49865c6cce1ae7d2fc7a3">flow::perf::Checkpointing_timer::Aggregator::clear</a></div><div class="ttdeci">void clear()</div><div class="ttdoc">Act as if aggregate() has never been called since construction.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00366">checkpt_timer.cpp:366</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator_html_af1c4f46ce680b979e98a3e255c88d063"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer_1_1Aggregator.html#af1c4f46ce680b979e98a3e255c88d063">flow::perf::Checkpointing_timer::Aggregator::m_timers</a></div><div class="ttdeci">std::vector&lt; Checkpointing_timer_ptr &gt; m_timers</div><div class="ttdoc">The ref-counted pointers to source timers passed to aggregate() in that order.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00713">checkpt_timer.hpp:713</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html">flow::perf::Checkpointing_timer</a></div><div class="ttdoc">The central class in the perf Flow module, this efficiently times the user's operation,...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00186">checkpt_timer.hpp:188</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a07204b9119b94bc10d53a8ba15c44797"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a07204b9119b94bc10d53a8ba15c44797">flow::perf::Checkpointing_timer::output</a></div><div class="ttdeci">void output(std::ostream *os) const</div><div class="ttdoc">Equivalent to (*os) &lt;&lt; (*this).</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00304">checkpt_timer.cpp:304</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a1d1506c1a9d63fb8f9856a1ce6a2f422"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a1d1506c1a9d63fb8f9856a1ce6a2f422">flow::perf::Checkpointing_timer::Checkpointing_timer</a></div><div class="ttdeci">Checkpointing_timer(Checkpointing_timer &amp;&amp;)=delete</div><div class="ttdoc">For now at least there's no reason for move-construction.</div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a1f03d654924a3724e1f051c119f3767b"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a1f03d654924a3724e1f051c119f3767b">flow::perf::Checkpointing_timer::checkpoints</a></div><div class="ttdeci">const std::vector&lt; Checkpoint &gt; &amp; checkpoints() const</div><div class="ttdoc">Returns the checkpoints recorded so far.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00299">checkpt_timer.cpp:299</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a25981d44a91e1315bd92711d6e18a91b"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a25981d44a91e1315bd92711d6e18a91b">flow::perf::Checkpointing_timer::m_name</a></div><div class="ttdeci">const std::string m_name</div><div class="ttdoc">The immutable human-readable name for this timer. It's const so no need for accessor for now.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00440">checkpt_timer.hpp:440</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a32ed9864d46708789d7418ab637ff382"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a32ed9864d46708789d7418ab637ff382">flow::perf::Checkpointing_timer::process_cpu_clock_types</a></div><div class="ttdeci">static Clock_types_subset process_cpu_clock_types()</div><div class="ttdoc">Returns the bit-set containing only those Clock_types enabled that measure passage of processor time ...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00084">checkpt_timer.cpp:84</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a378be385d0c3dda261c8944551280010"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a378be385d0c3dda261c8944551280010">flow::perf::Checkpointing_timer::scale</a></div><div class="ttdeci">void scale(uint64_t mult_scale, uint64_t div_scale)</div><div class="ttdoc">Called anytime after the last checkpoint(), this modifies the data collected so far to be as if every...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00100">checkpt_timer.cpp:100</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a3b73f2812c2bf6a27ef2becc13859d73"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a3b73f2812c2bf6a27ef2becc13859d73">flow::perf::Checkpointing_timer::now</a></div><div class="ttdeci">Time_pt_set now() const</div><div class="ttdoc">Sample all currently enabled Clock_types' clocks and return those values, each of which is a time sta...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00241">checkpt_timer.cpp:241</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a4c26ee75e58df6abc3b59083f920897c"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a4c26ee75e58df6abc3b59083f920897c">flow::perf::Checkpointing_timer::operator=</a></div><div class="ttdeci">void operator=(Checkpointing_timer &amp;&amp;)=delete</div><div class="ttdoc">No copy assignment; no move assignment either.</div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a66605dd59939ddc69d7f8fde19a5ed7c"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a66605dd59939ddc69d7f8fde19a5ed7c">flow::perf::Checkpointing_timer::m_last_checkpoint_when</a></div><div class="ttdeci">Time_pt_set m_last_checkpoint_when</div><div class="ttdoc">The value of now() recorded during the last checkpoint() call; or equals m_start_when if checkpoint()...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00529">checkpt_timer.hpp:529</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a7c799f400ceddd5ad5529fa66f026fd0"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a7c799f400ceddd5ad5529fa66f026fd0">flow::perf::Checkpointing_timer::now_cpu_lo_res_raw</a></div><div class="ttdeci">static Cpu_split_clock_durs_since_epoch now_cpu_lo_res_raw()</div><div class="ttdoc">Returns the current Cpu_split_clock time, essentially as a combo struct containing raw (integer) coun...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00246">checkpt_timer.cpp:246</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a82e717d5b1f6df56dc70b26c7da100f3"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a82e717d5b1f6df56dc70b26c7da100f3">flow::perf::Checkpointing_timer::now_cpu_lo_res</a></div><div class="ttdeci">static Time_pt now_cpu_lo_res(const Cpu_split_clock_durs_since_epoch &amp;cpu_combo_now_raw, bool user_else_sys)</div><div class="ttdoc">Returns individual Time_pt value returnable by now() various overloads: either the user time or syste...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00252">checkpt_timer.cpp:252</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a886e2150b2918df43c53d4850205e1c8"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a886e2150b2918df43c53d4850205e1c8">flow::perf::Checkpointing_timer::Checkpointing_timer</a></div><div class="ttdeci">Checkpointing_timer(const Checkpointing_timer &amp;src)=default</div><div class="ttdoc">Constructs a timer that is identical to but entirely independent of the source object.</div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a959a0446aa6a0b6db59e9892d8f0a699"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a959a0446aa6a0b6db59e9892d8f0a699">flow::perf::Checkpointing_timer::real_clock_types</a></div><div class="ttdeci">static Clock_types_subset real_clock_types()</div><div class="ttdoc">Returns the bit-set containing only those Clock_types enabled that measure passage of real (wall cloc...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00077">checkpt_timer.cpp:77</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a9d064df3b46dd7e629f4d836a9803750"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a9d064df3b46dd7e629f4d836a9803750">flow::perf::Checkpointing_timer::m_checkpoints</a></div><div class="ttdeci">std::vector&lt; Checkpoint &gt; m_checkpoints</div><div class="ttdoc">The checkpoints recorded so far, in order, one per checkpoint() call.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00535">checkpt_timer.hpp:535</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_a9e6078df059d5626ab5774f0a33fbad7"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#a9e6078df059d5626ab5774f0a33fbad7">flow::perf::Checkpointing_timer::checkpoint</a></div><div class="ttdeci">const Checkpoint &amp; checkpoint(std::string &amp;&amp;name_moved)</div><div class="ttdoc">Records a checkpoint, which takes a sample of all enabled Clock_types' clocks and records the corresp...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00272">checkpt_timer.cpp:272</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_aa9940d8e87883f9985ba18939f833db9"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#aa9940d8e87883f9985ba18939f833db9">flow::perf::Checkpointing_timer::Checkpointing_timer</a></div><div class="ttdeci">Checkpointing_timer(log::Logger *logger_ptr, std::string &amp;&amp;name_moved, Clock_types_subset which_clocks, size_t max_n_checkpoints)</div><div class="ttdoc">Constructs a new timer and immediately begins measuring time, in that the next checkpoint() call will...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00029">checkpt_timer.cpp:29</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_aabebe01d0d5096618a8a7c2cf52320fb"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#aabebe01d0d5096618a8a7c2cf52320fb">flow::perf::Checkpointing_timer::thread_cpu_clock_types</a></div><div class="ttdeci">static Clock_types_subset thread_cpu_clock_types()</div><div class="ttdoc">Returns the bit-set containing only those Clock_types enabled that measure passage of processor time ...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00093">checkpt_timer.cpp:93</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_ac16b16c3192e287ae3f08be786626f1a"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#ac16b16c3192e287ae3f08be786626f1a">flow::perf::Checkpointing_timer::m_start_when</a></div><div class="ttdeci">Time_pt_set m_start_when</div><div class="ttdoc">The value of now() saved in public constructor, marking the time point when the timing began.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00520">checkpt_timer.hpp:520</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_ac5518c3fdc58f8867ca114186562575b"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#ac5518c3fdc58f8867ca114186562575b">flow::perf::Checkpointing_timer::m_which_clocks</a></div><div class="ttdeci">const Clock_types_subset m_which_clocks</div><div class="ttdoc">The bit-set indexed by size_t(Clock_type::...) wherein that clock will be sampled in now() and checkp...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00512">checkpt_timer.hpp:512</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_ac8c6a294890c7b59b79555c8116be552"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#ac8c6a294890c7b59b79555c8116be552">flow::perf::Checkpointing_timer::operator=</a></div><div class="ttdeci">void operator=(const Checkpointing_timer &amp;)=delete</div><div class="ttdoc">Disallow overwriting. Copy-construction exists for a specific pattern to be possible; no need for thi...</div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_ae1983df5bfc263f2d4075e26f95cc544"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#ae1983df5bfc263f2d4075e26f95cc544">flow::perf::Checkpointing_timer::Cpu_split_clock</a></div><div class="ttdeci">boost::chrono::process_cpu_clock Cpu_split_clock</div><div class="ttdoc">chrono clock used, internally, for Clock_type::S_CPU_USER_LO_RES and Clock_type::S_CPU_SYS_LO_RES que...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00452">checkpt_timer.hpp:452</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_af14cca9bf47de862b19f04a9348de234"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#af14cca9bf47de862b19f04a9348de234">flow::perf::Checkpointing_timer::Cpu_split_clock_durs_since_epoch</a></div><div class="ttdeci">Cpu_split_clock::times Cpu_split_clock_durs_since_epoch</div><div class="ttdoc">Short-hand for the combo (user/kernel) durations-since-epoch tracked by Cpu_split_clock.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00455">checkpt_timer.hpp:455</a></div></div>
<div class="ttc" id="aclassflow_1_1perf_1_1Checkpointing__timer_html_afeb1faa0e4962dacf9b6a134191a4933"><div class="ttname"><a href="classflow_1_1perf_1_1Checkpointing__timer.html#afeb1faa0e4962dacf9b6a134191a4933">flow::perf::Checkpointing_timer::since_start</a></div><div class="ttdeci">Duration_set since_start() const</div><div class="ttdoc">Returns the duration(s) (for all enabled Clock_types) between construction and the last checkpoint() ...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00293">checkpt_timer.cpp:293</a></div></div>
<div class="ttc" id="aclock__type__fwd_8hpp_html"><div class="ttname"><a href="clock__type__fwd_8hpp.html">clock_type_fwd.hpp</a></div></div>
<div class="ttc" id="alog_8hpp_html"><div class="ttname"><a href="log_8hpp.html">log.hpp</a></div></div>
<div class="ttc" id="anamespaceflow_1_1perf_html"><div class="ttname"><a href="namespaceflow_1_1perf.html">flow::perf</a></div><div class="ttdoc">Flow module containing tools for profiling and optimization.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00024">checkpt_timer.cpp:25</a></div></div>
<div class="ttc" id="anamespaceflow_1_1perf_html_a09ba385403a0f347f283659a6e9d971b"><div class="ttname"><a href="namespaceflow_1_1perf.html#a09ba385403a0f347f283659a6e9d971b">flow::perf::Checkpointing_timer_ptr</a></div><div class="ttdeci">boost::shared_ptr&lt; Checkpointing_timer &gt; Checkpointing_timer_ptr</div><div class="ttdoc">Short-hand for ref-counting pointer to Checkpointing_timer.</div><div class="ttdef"><b>Definition:</b> <a href="perf__fwd_8hpp_source.html#l00043">perf_fwd.hpp:43</a></div></div>
<div class="ttc" id="anamespaceflow_1_1perf_html_a5bb3a068357516df714c4266ec5c3df4"><div class="ttname"><a href="namespaceflow_1_1perf.html#a5bb3a068357516df714c4266ec5c3df4">flow::perf::operator&lt;&lt;</a></div><div class="ttdeci">std::ostream &amp; operator&lt;&lt;(std::ostream &amp;os, const Checkpointing_timer::Checkpoint &amp;checkpoint)</div><div class="ttdoc">Prints string representation of the given Checkpoint to the given ostream.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8cpp_source.html#l00335">checkpt_timer.cpp:335</a></div></div>
<div class="ttc" id="anamespaceflow_1_1perf_html_aabd93a8a40158585ed149742d8937601"><div class="ttname"><a href="namespaceflow_1_1perf.html#aabd93a8a40158585ed149742d8937601">flow::perf::Clock_types_subset</a></div><div class="ttdeci">std::bitset&lt; size_t(Clock_type::S_END_SENTINEL)&gt; Clock_types_subset</div><div class="ttdoc">Short-hand for a bit-set of N bits which represents the presence or absence of each of the N possible...</div><div class="ttdef"><b>Definition:</b> <a href="clock__type__fwd_8hpp_source.html#l00164">clock_type_fwd.hpp:164</a></div></div>
<div class="ttc" id="anamespaceflow_1_1perf_html_ace5f154155a7d9d5c112c1a83aa04fb5"><div class="ttname"><a href="namespaceflow_1_1perf.html#ace5f154155a7d9d5c112c1a83aa04fb5">flow::perf::Time_pt</a></div><div class="ttdeci">Fine_time_pt Time_pt</div><div class="ttdoc">Short-hand for a high-precision boost.chrono point in time, formally equivalent to flow::Fine_time_pt...</div><div class="ttdef"><b>Definition:</b> <a href="clock__type__fwd_8hpp_source.html#l00033">clock_type_fwd.hpp:33</a></div></div>
<div class="ttc" id="anamespaceflow_1_1perf_html_ad61fb186191e4bb824d14601d11a2eb0"><div class="ttname"><a href="namespaceflow_1_1perf.html#ad61fb186191e4bb824d14601d11a2eb0">flow::perf::Clock_type</a></div><div class="ttdeci">Clock_type</div><div class="ttdoc">Clock types supported by flow::perf module facilities, perf::Checkpointing_timer in particular.</div><div class="ttdef"><b>Definition:</b> <a href="clock__type__fwd_8hpp_source.html#l00066">clock_type_fwd.hpp:67</a></div></div>
<div class="ttc" id="aperf__fwd_8hpp_html"><div class="ttname"><a href="perf__fwd_8hpp.html">perf_fwd.hpp</a></div></div>
<div class="ttc" id="astructflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint_html"><div class="ttname"><a href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html">flow::perf::Checkpointing_timer::Checkpoint</a></div><div class="ttdoc">The entirety of the information recorded with each Checkpointing_timer::checkpoint() call; it contain...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00203">checkpt_timer.hpp:204</a></div></div>
<div class="ttc" id="astructflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint_html_a6c0363e3e1ef330464b87363e4287758"><div class="ttname"><a href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html#a6c0363e3e1ef330464b87363e4287758">flow::perf::Checkpointing_timer::Checkpoint::m_name</a></div><div class="ttdeci">const std::string m_name</div><div class="ttdoc">User-supplied name of the checkpoint.</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00206">checkpt_timer.hpp:206</a></div></div>
<div class="ttc" id="astructflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint_html_aacbec1a1e5600aeac4e7ca876060552f"><div class="ttname"><a href="structflow_1_1perf_1_1Checkpointing__timer_1_1Checkpoint.html#aacbec1a1e5600aeac4e7ca876060552f">flow::perf::Checkpointing_timer::Checkpoint::m_since_last</a></div><div class="ttdeci">Duration_set m_since_last</div><div class="ttdoc">For the T.checkpoint() call that generated *this, for each enabled Clock_type: Time elapsed since eit...</div><div class="ttdef"><b>Definition:</b> <a href="checkpt__timer_8hpp_source.html#l00212">checkpt_timer.hpp:212</a></div></div>
<div class="ttc" id="astructflow_1_1perf_1_1Duration__set_html"><div class="ttname"><a href="structflow_1_1perf_1_1Duration__set.html">flow::perf::Duration_set</a></div><div class="ttdoc">Convenience wrapper around an array&lt;Duration, N&gt;, which stores a duration for each of the N possible ...</div><div class="ttdef"><b>Definition:</b> <a href="clock__type__fwd_8hpp_source.html#l00185">clock_type_fwd.hpp:186</a></div></div>
<div class="ttc" id="astructflow_1_1perf_1_1Time__pt__set_html"><div class="ttname"><a href="structflow_1_1perf_1_1Time__pt__set.html">flow::perf::Time_pt_set</a></div><div class="ttdoc">Convenience wrapper around an array&lt;Time_pt, N&gt;, which stores a time point for each of the N possible...</div><div class="ttdef"><b>Definition:</b> <a href="clock__type__fwd_8hpp_source.html#l00195">clock_type_fwd.hpp:196</a></div></div>
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